Combinatorial synthesis of novel materials

ABSTRACT

Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

This application is a divisional of U.S. patent application Ser. No.08/327,513, filed Oct. 18, 1994 now U.S. Pat. No. 5,985,356, and refiledas a Continuing Prosecution Application on Jun. 24, 1998.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with Government support pursuant to Contract No.DE-AC03-76SF00098 awarded by the Department of Energy. The Governmenthas certain rights in this invention.

FIELD OF THE INVENTION

The present invention generally relates to methods and apparatus for theparallel deposition, synthesis and screening of an array of diversematerials at known locations on a single substrate surface. Theinvention may be applied, for example, to prepare covalent networksolids, ionic solids and molecular solids. More specifically, theinvention may be applied to prepare inorganic materials, intermetallicmaterials, metal alloys, ceramic materials, organic materials,organometallic materials, non-biological organic polymers, compositematerials (e.g., inorganic composites, organic composites, orcombinations thereof), etc. Once prepared, these materials can bescreened in parallel for useful properties including, for example,electrical, thermal, mechanical, morphological, optical, magnetic,chemical, and other properties.

BACKGROUND OF THE INVENTION

The discovery of new materials with novel chemical and physicalproperties often leads to the development of new and usefultechnologies. Over forty years ago, for example, the preparation ofsingle crystal semiconductors transformed the electronics industry.Currently, there is a tremendous amount of activity being carried out inthe areas of superconductivity, magnetic materials, phosphors, nonlinearoptics and high strength materials. Unfortunately, even though thechemistry of extended solids has been extensively explored, few generalprinciples have emerged that allow one to predict with certaintycomposition, structure and reaction pathways for the synthesis of suchsolid state compounds. Moreover, it is difficult to predict a priori thephysical properties a particular three dimensional structure willpossess. Consider, for example, the synthesis of the YBa₂Cu₃O⁷⁻⁸superconductor in 1987. Soon after the discovery of theLa_(2−x)Sr_(x)CuO₄ superconductor, which adopts the K₂NiF₄ structure(Bednorz, J. G. and K. A. Muller, Z. Phy. B 64:189 (1986), it wasobserved that the application of pressure increased the transitiontemperature (Chu, et al., Phys. Rev. Lett. 58:405 (1987)). As such, Chu,et al. attempted to synthesize a Y-Ba-Cu-O compound of the samestoichiometry in the hope that substitution of the smaller element,i.e., yttrium, for lanthanum would have the same effect. Although theyfound superconductivity above 93K, no phase with K₂NiF₄ structure wasobserved (Wu, et al., Phys. Rev. Lett. 58:908 (1987)). Even for therelatively simple intermetallic compounds, such as the binary compoundsof nickel and zirconium (Ni₅Zr, Ni₇Zr₂, Ni₃Zr, Ni₂Zr₈, Ni₁₀Zr₇, Ni₁₁Zr₉,NiZr and NiZr₂), it is not yet understood why only certainstoichiometries occur.

Clearly, the preparation of new materials with novel chemical andphysical properties is at best happenstance with our current level ofunderstanding. Consequently, the discovery of new materials dependslargely on the ability to synthesize and analyze new compounds. Givenapproximately 100 elements in the periodic table which can be used tomake compositions consisting of three, four, five, six or more elements,the universe of possible new compounds remains largely unexplored. Assuch, there exists a need in the art for a more efficient, economicaland systematic approach for the synthesis of novel materials and for thescreening of such materials for useful properties.

One of the processes whereby nature produces molecules having novelfunctions involves the generation of large collections (libraries) ofmolecules and the systematic screening of those libraries for moleculeshaving a desired property. An example of such a process is the humoralimmune system which in a matter of weeks sorts through some 10¹²antibody molecules to find one which specifically binds a foreignpathogen (Nisonoff, et al., The Antibody Molecule (Academic Press, NewYork, 1975)). This notion of generating and screening large libraries ofmolecules has recently been applied to the drug discovery process. Thediscovery of new drugs can be likened to the process of finding a keywhich fits a lock of unknown structure. One solution to the problem isto simply produce and test a large number of different keys in the hopethat one will fit the lock.

Using this logic, methods have been developed for the synthesis andscreening of large libraries (up to 10¹⁴ molecules) of peptides,oligonucleotides and other small molecules. Geysen, et al., for example,have developed a method wherein peptide syntheses are carried out inparallel on several rods or pins (see, J. Immun. Meth. 102:259-274(1987), incorporated herein by reference for all purposes). Generally,the Geysen, et al. method involves functionalizing the termini ofpolymeric rods and sequentially immersing the termini in solutions ofindividual amino acids. In addition to the Geysen, et al. method,techniques have recently been introduced for synthesizing large arraysof different peptides and other polymers on solid surfaces. Pirrung, etal., have developed a technique for generating arrays of peptides andother molecules using, for example, light-directed,spatially-addressable synthesis techniques (see, U.S. Pat. No. 5,143,854and PCT Publication No. WO 90/15070, incorporated herein by referencefor all purposes). In addition, Fodor, et al. have developed, amongother things, a method of gathering fluorescence intensity data, variousphotosensitive protecting groups, masking techniques, and automatedtechniques for performing light-directed, spatially-addressablesynthesis techniques (see, Fodor, et al., PCT Publication No. WO92/10092, the teachings of which are incorporated herein by referencefor all purposes).

Using these various methods, arrays containing thousands or millions ofdifferent elements can be formed (see, U.S. patent application Ser. No.805,727, filed Dec. 6, 1991, which issued as U.S. Pat. No. 5,424,186 onJun. 13, 1995, the teachings of which are incorporated herein byreference for all purposes). As a result of their relationship tosemiconductor fabrication techniques, these methods have come to bereferred to as “Very Large Scale Immobilized Polymer Synthesis,” or“VLSIPS™” technology. Such techniques have met with substantial successin, for example, screening various ligands such as peptides andoligonucleotides to determine their relative binding affinity to areceptor such as an antibody.

The solid phase synthesis techniques currently being used to preparesuch libraries involve the stepwise, i.e., sequential, coupling ofbuilding blocks to form the compounds of interest. In the Pirrung, etal. method, for example, polypeptide arrays are synthesized on asubstrate by attaching photoremovable groups to the surface of thesubstrate, exposing selected regions of the substrate to light toactivate those regions, attaching an amino acid monomer with aphotoremovable group to the activated region, and repeating the steps ofactivation and attachment until polypeptides of the desired length andsequences are synthesized. These solid phase synthesis techniques, whichinvolve the sequential coupling of building blocks (e.g., amino acids)to form the compounds of interest, cannot readily be used to preparemany inorganic and organic compounds.

From the above, it is seen that a method and apparatus for synthesizingand screening libraries of materials, such as inorganic materials, atknown locations on a substrate is desired.

SUMMARY OF THE INVENTION

The present invention provides methods and apparatus for the preparationand use of a substrate having an array of diverse materials inpredefined regions thereon. A substrate having an array of diversematerials thereon is prepared by delivering components of materials topredefined regions on the substrate, and simultaneously reacting thecomponents to form at least two materials. Materials which can beprepared using the methods and apparatus of the present inventioninclude, for example, covalent network solids, ionic solids andmolecular solids. More particularly, materials which can be preparedinclude inorganic materials, intermetallic materials, metal alloys,ceramic materials, organic materials, organometallic materials,non-biological organic polymers, composite materials (e.g., inorganiccomposites, organic composites, or combinations thereof), etc. Onceprepared, these materials can be screened in parallel for usefulproperties including, for example, electrical, thermal, mechanical,morphological, optical, magnetic, chemical and other properties. Assuch, the present invention provides methods and apparatus for theparallel synthesis and analysis of novel materials having new and usefulproperties. Any material found to possess a useful property can besubsequently prepared on a large-scale.

In one embodiment of the present invention, a first component of a firstmaterial is delivered to a first region on a substrate, and a firstcomponent of a second material is delivered to a second region on thesame substrate. Thereafter, a second component of the first material isdelivered to the first region on the substrate, and a second componentof the second material is delivered to the second region on thesubstrate. The process is optionally repeated, with additionalcomponents, to form a vast array of components at predefined, i.e.,known, locations on the substrate. Thereafter, the components aresimultaneously reacted to form at least two materials. The componentscan be sequentially or simultaneously delivered to predefined regions onthe substrate in any stoichiometry, including a gradient ofstoichiometries, using any of a number of different delivery techniques.

In another embodiment of the present invention, a method is provided forforming at least two different arrays of materials by deliveringsubstantially the same reaction components at substantially identicalconcentrations to reaction regions on both first and second substratesand, thereafter, subjecting the components on the first substrate to afirst set of reaction conditions and the components on the secondsubstrate to a second set of reaction conditions. Using this method, theeffects of the various reaction parameters can be studied on manymaterials simultaneously and, in turn, such reaction parameters can beoptimized. Reaction parameters which can be varied include, for example,reactant amounts, reactant solvents, reaction temperatures, reactiontimes, the pressures at which the reactions are carried out, theatmospheres in which the reactions are conducted, the rates at which thereactions are quenched, the order in which the reactants are deposited,etc.

In the delivery systems of the present invention, a small, preciselymetered amount of each reactant component is delivered into eachreaction region. This may be accomplished using a variety of deliverytechniques, either alone or in combination with a variety of maskingtechniques. For example, thin-film deposition in combination withphysical masking or photolithographic techniques can be used to delivervarious reactants to selected regions on the substrate. Reactants can bedelivered as amorphous films, epitaxial films, or lattice andsuperlattice structures. Moreover, using such techniques, reactants canbe delivered to each site in a uniform distribution, or in a gradient ofstoichiometries. Alternatively, the various reactant components can bedeposited into the reaction regions of interest from a dispenser in theform of droplets or powder. Suitable dispensers include, for example,micropipettes, mechanisms adapted from ink-jet printing technology, orelectrophoretic pumps.

Once the components of interest have been delivered to predefinedregions on the substrate, they can be reacted using a number ofdifferent synthetic routes to form an array of materials The componentscan be reacted using, for example, solution based synthesis techniques,photochemical techniques, polymerization techniques, template directedsynthesis techniques, epitaxial growth techniques, by the sol-gelprocess, by thermal, infrared or microwave heating, by calcination,sintering or annealing, by hydrothermal methods, by flux methods, bycrystallization through vaporization of solvent, etc. Thereafter, thearray can be screened for materials having useful properties.

In another embodiment of the present invention, an array of inorganicmaterials on a single substrate at predefined regions thereon isprovided. Such an array can consists of more than 10, 10², 10³, 10⁴, 10⁵or 10⁶ different inorganic compounds. It should be noted that whengradient libraries are prepared in each of the predefined reactionregions, a virtually infinite number of inorganic materials can beprepared on a single substrate. In some embodiments, the density ofregions per unit area will be greater than 0.04 regions/cm², morepreferably greater than 0.1 regions/cm², even more preferably greaterthan 1 region/cm², even more preferably greater than 10 regions/cm², andstill more preferably greater than 100 regions/cm². In most preferredembodiments, the density of regions per unit area will be greater than1,000 regions/cm², more preferably 10,000 regions/cm², even morepreferably greater than 100,000 regions/cm², and still more preferably10,000,000 regions/cm².

In yet another aspect, the present invention provides a material havinga useful property prepared by: forming an array of materials on a singlesubstrate; screening the array for a materials having a useful property;and making additional amounts of the material having the usefulproperty. As such, the present invention provides methods and apparatusfor the parallel synthesis and analysis of novel materials having newand useful properties.

A further understanding of the nature and advantages of the inventionsherein may be realized by reference to the remaining portions of thespecification and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a reaction system employing an eight RFmagnetron sputtering gun.

FIG. 2 illustrates masking of a substrate at a first location. Thesubstrate is shown in cross-section;

FIGS. 3A-3I illustrate the use of binary masking techniques to generatean array of reactants on a single substrate;

FIGS. 4A-4I illustrate the use of physical masking techniques togenerate an array of reactants on a single substrate;

FIGS. 5A-5M illustrate the use of physical masking techniques togenerate an array of reactants on a single substrate;

FIG. 6 displays the elements of a typical guided droplet dispenser thatmay be used to delivery the reactant solution of the present invention;

FIG. 7 illustrates an example of a Scanning RF Susceptibility DetectionSystem which can be used to detect the superconductivity of an array ofmaterials;

FIG. 8 is a map of the reactant components delivered to the 16predefined regions on the MgO substrate;

FIG. 9 is a photograph of the array of 16 different compounds on the1.25 cm×1.25 cm MgO substrate; and

FIGS. 10A-10B illustrate the resistance of the two conducting materialsas a function of temperature.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS Contents

I. Glossary

II. General Overview

III. Isolation of Reaction Regions on The Substrate

IV. Methods For Delivery Of Reactant Components

A. Delivery Using Thin-Film Deposition Techniques

B. Delivery Using A Dispenser

V. Moving The Dispenser With Respect To The Substrate

VI. Synthetic Routes For Reacting The Array Of Components

VII. Methods For Screening An Array Of Materials

VIII. Alternative Embodiments

IX. Examples

A. Synthesis of An Array of Copper Oxide Thin-Film Materials

B. Synthesis of An Array of 16 Different Organic Polymers

C. Synthesis of An Array of Different Zeolites

D. Synthesis of An Array of Copper Oxide Compounds Using SprayingDeposition Techniques

E. Synthesis of An Array of Manganese Oxide Thin-film Materials

X. Conclusion

I. Glossary

The following terms are intended to have the following general meaningsas they are used herein.

1. Substrate: A material having a rigid or semi-rigid surface. In manyembodiments, at least one surface of the substrate will be substantiallyflat, although in some embodiments it may be desirable to physicallyseparate synthesis regions for different materials with, for example,dimples, wells, raised regions, etched trenches, or the like. In someembodiments, the substrate itself contains wells, raised regions, etchedtrenches, etc. which form all or part of the synthesis regions.According to other embodiments, small beads or pellets may be providedon the surface within dimples or on other regions of the surface or,alternatively, the small beads or pellets may themselves be thesubstrate.

2. Predefined Region: A predefined region is a localized area on asubstrate which is, was, or is intended to be used for formation of aselected material and is otherwise referred to herein in the alternativeas “known” region, “reaction” region, a “selected” region, or simply a“region.” The predefined region may have any convenient shape, e.g.,circular, rectangular, elliptical, wedge-shaped, etc. Additionally, thepredefined region, i.e., the reaction site, can be a bead or pelletwhich is coated with a reactant component(s) of interest. In thisembodiment, the bead or pellet can be identified with a tag, such as anetched binary bar code that can be used to indicate the history of thebead or pellet, i.e., to identify which components were depositedthereon. In some embodiments, a predefined region and, therefore, thearea upon which each distinct material is synthesized is smaller thanabout 25 cm², preferably less than 10 cm², more preferably less than 5cm², even more preferably less than 1 cm², still more preferably lessthan 1 mm², and even more preferably less than 0.5 mm². In mostpreferred embodiments, the regions have an area less than about 10,000μm², preferably less than 1,000 μm², more preferably less than 100 μm²,and even more preferably less than 10 μm².

3. Radiation: Energy which may be selectively applied including energyhaving a wavelength between 10⁻¹⁴ and 10⁴ meters including, for example,electron beam radiation, gamma radiation, x-ray radiation, ultravioletradiation, visible light, infrared radiation, microwave radiation andradio waves. “Irradiation” refers to the application of radiation to asurface.

4. Component: “Component” is used herein to refer to each of theindividual chemical substances that act upon one another to produce aparticular material and is otherwise referred to herein in thealternative as “reactant” or “reactant component.” That is to say, thecomponents or, alternatively, reactants are the molecules that act uponone another to produce a new molecule(s), i.e., product(s); for example,in the reaction HCl+NaOH→NaCl+H₂O, the HCl and the NaOH are thecomponents or reactants.

5. Material: The term “material” is used herein to refer to solid-statecompounds, extended solids, extended solutions, clusters of molecules oratoms, crystals, etc.

6. Covalent Network Solids: Solids that consist of atoms held togetherin a large network of chains by covalent bonds. Such covalent networksolids include, but are not limited to, diamond, silicon nitride,graphite, bunkmisterfillerene and organic polymers which cannot besynthesized in a stepwise fashion.

7. Ionic Solids: Solids which can be modeled as cations and anions heldtogether by electrical attraction of opposite charge. Such ionic solidsinclude, but are not restricted to, CaF₂, CdCl₂, ZnCl₂, NaCl₂, AgF,AgCl, AgBr and spinels (e.g., ZnAl₂O₄, MgAl₂O₄, FrCr₂O₄, etc.).

8. Molecular Solids: Solids consisting of atoms or molecules heldtogether by intermolecular forces. Molecular solids include, but are notlimited to, extended solids, solid neon, organic compounds, synthetic ororganic metals (e.g., tetrathiafulvalene-tetracyanoquinonedimethane(TTF-TCNQ)), liquid crystals (e.g., cyclic siloxanes) and proteincrystals.

9. Inorganic Materials: Materials which do not contain carbon as aprincipal element. The oxides and sulphides of carbon and the metalliccarbides are considered inorganic materials. Examples of inorganiccompounds which can be synthesized using the methods of the presentinvention include, but are not restricted to, the following:

(a) Intermetallics (or Intermediate Constituents): Intermetalliccompounds constitute a unique class of metallic materials that formlong-range ordered crystal structures below a critical temperature. Suchmaterials form when atoms of two metals combine in certain proportionsto form crystals with a different structure from that of either of thetwo metals (e.g., NiAl, CrBe₂, CuZn, etc.).

(b) Metal Alloys: A substance having metallic properties and which iscomposed of a mixture of two or more chemical elements of which at leastone is a metal.

(c) Magnetic Alloys: An alloy exhibiting ferromagnetism such as siliconiron, but also iron-nickel alloys, which may contain small amounts ofany of a number of other elements (e.g., copper, aluminum, chromium,molybdenum, vanadium, etc.), and iron-cobalt alloys.

(d) Ceramics: Typically, a ceramic is a metal oxide, boride, carbide,nitride, or a mixture of such materials. In addition, ceramics areinorganic, nonmetallic products that are subjected to high temperatures(i.e., above visible red, 540° C. to 1000° C.) during manufacture oruse. Such materials include, for example, alumina, zirconium, siliconcarbide, aluminum nitride, silicon nitride, the YBa₂Cu₃O⁷⁻⁸superconductor, ferrite (BaFe₁₂O₁₉), Zeolite A(Na₁₂[(SiO₂)₁₂(AlO₂)].27H₂O), soft and permanent magnets, etc. Hightemperature superconductors are illustrative of materials that can beformed and screened using the present invention. “High temperaturesuperconductors” include, but are not restricted to, theLa_(2−x)Sr_(x)CuO₄ superconductors, the Bi₂CaSr₂Cu₂O_(8+x)superconductors, the Ba_(1−x)K_(x)BiO₃ superconductors and the ReBaCusuperconductors. Such high temperature superconductors will, when theyhave the desired properties, have critical temperatures above 30° K,preferably above 50° K, and more preferably above 70° K.

10. Organic Materials: Compounds, which generally consist of carbon andhydrogen, with or without oxygen, nitrogen or other elements, exceptthose in which carbon does not play a critical role (e.g., carbonatesalts). Examples of organic materials which can be synthesized using themethods of the present invention include, but are not restricted to, thefollowing:

(a) Non-biological, organic polymers: Nonmetallic materials consistingof large macromolecules composed of many repeating units. Such materialscan be either natural or synthetic, cross-linked or non-crosslinked, andthey may be homopolymers, copolymers, or higher-ordered polymers (e.g.,terpolymers, etc.). By “non-biological,” α-amino acids and nucleotidesare excluded. More particularly, “non-biological, organic polymers”exclude those polymers which are synthesized by a linear, stepwisecoupling of building blocks. Examples of polymers which can be preparedusing the methods of the present invention include, but are not limitedto, the following: polyurethanes, polyesters, polycarbonates,polyethyleneimines, polyacetates, polystyrenes, polyamides,polyanilines, polyacetylenes, polypyrroles, etc.

11. Organometallic Materials: A class of compounds of the type R-M,wherein carbon atoms are linked directly with metal atoms (e.g., leadtetraethyl (Pb(C₂H₅)₄), sodium phenyl (C₆H₅.Na), zinc dimethyl(Zn(CH₃)₂), etc.).

12. Composite Materials: Any combination of two materials differing inform or composition on a macroscale. The constituents of compositematerials retain their identities, i.e., they do not dissolve or mergecompletely into one another although they act in concert. Such compositematerials may be inorganic, organic or a combination thereof. Includedwithin this definition are, for example, doped materials, dispersedmetal catalysts and other heterogeneous solids.

II. General Overview

The present invention provides methods and apparatus for the preparationand use of a substrate having an array of materials in predefinedregions thereon. The invention is described herein primarily with regardto the preparation of inorganic materials, but can readily be applied inthe preparation of other materials. Materials which can be prepared inaccordance with the methods of the present invention include, forexample, covalent network solids, ionic solids and molecular solids.More particularly, materials which can be prepared in accordance withthe methods of the present invention include, but are not limited to,inorganic materials, intermetallic materials, metal alloys, ceramicmaterials, organic materials, organometallic materials, non-biologicalorganic polymers, composite materials (e.g., inorganic composites,organic composites, or combinations thereof), or other materials whichwill be apparent to those of skill in the art upon review of thisdisclosure.

The resulting substrate having an array of materials thereon will have avariety of uses. For example, once prepared, the substrate can bescreened for materials having useful properties. Accordingly, the arrayof materials is preferably synthesized on a single substrate. Bysynthesizing the array of materials on a single substrate, screening thearray for materials having useful properties is more easily carried out.Alternatively, however, the array of materials can be synthesized on aseries of beads or pellets by depositing on each bead or pellet thecomponents of interest. In this embodiment, each bead or pellet willhave a tag which indicates the history of components deposited thereonas well as their stoichiometries. The tag can, for example, be a binarytag etched into the surface of the bead so that it can be read usingspectroscopic techniques. As with the single substrate having an arrayof materials thereon, each of the individual beads or pellets can bescreened for useful properties.

Properties which can be screened for include, for example, electrical,thermal, mechanical, morphological, optical, magnetic, chemical, etc.More particularly, properties which can be screened for include, forexample, conductivity, super-conductivity, resistivity, thermalconductivity, anisotropy, hardness, crystallinity, optical transparency,magnetoresistance, permeability, frequency doubling, photoemission,coercivity, critical current, or other useful properties which will beapparent to those of skill in the art upon review of this disclosure.Importantly, the synthesizing and screening of a diverse array ofmaterials enables new compositions with new physical properties to beidentified. Any material found to possess a useful property can besubsequently prepared on a large-scale. It will be apparent to those ofsill in the art that once identified using the methods of the presentinvention, a variety of different methods can be used to prepare suchuseful materials on a large or bulk scale with essentially the samestructure and properties.

Generally, the array of materials is prepared by successively deliveringcomponents of materials to predefined regions on a substrate, andsimultaneously reacting the components to form at least two materials.In one embodiment, for example, a first component of a first material isdelivered to a first region on a substrate, and a first component of asecond material is delivered to a second region on the same substrate.Thereafter, a second component of the first material is delivered to thefirst regions on the substrate, and a second component of the secondmaterial is delivered to the second region on the substrate. Eachcomponent can be delivered in either a uniform or gradient fashion toproduce either a single stoichiometry or, alternatively, a large numberof stoichiometries within a single predefined region. Moreover,reactants can be delivered as amorphous films, epitaxial films, orlattice or superlattice structures. The process is repeated, withadditional components, to form a vast array of components at predefined,i.e., known, locations on the substrate. Thereafter, the components aresimultaneously reacted to form at least two materials. As explainedhereinbelow, the components can be sequentially or simultaneouslydelivered to predefined regions on the substrate using any of a numberof different delivery techniques.

In the methods of the present invention, the components, after beingdelivered to predefined regions on the substrate, can be reacted using anumber of different synthetic routes. For example, the components can bereacted using, for example, solution based synthesis techniques,photochemical techniques, polymerization techniques, template directedsynthesis techniques,. epitaxial growth techniques, by the sol-gelprocess, by thermal, infrared or microwave heating, by calcination,sintering or annealing, by hydrothermal methods, by flux methods, bycrystallization through vaporization of solvent, etc. Other usefulsynthesis techniques that can be used to simultaneously react thecomponents of interest will be readily apparent to those of skill in theart.

Since the reactions are conducted in parallel, the number of reactionsteps can be minimized. Moreover, the reaction conditions at differentreaction regions can be controlled independently. As such, reactantamounts, reactant solvents, reaction temperatures, reaction times, therates at which the reactions are quenched, deposition order ofreactants, etc. can be varied from reaction region to reaction region onthe substrate. Thus, for example, the first component of the firstmaterial and the first component of the second material can be the sameor different. If the first component of the first material is the sameas the first component of the second materials, this component can beoffered to the first and second regions on the substrate at either thesame or different concentrations. This is true as well for the secondcomponent of the first material and the second component of the secondmaterial, etc. As with the first component of the first and secondmaterials, the second component of the first material and the secondcomponent of the second material can be the same or different and, ifthe same, this component can be offered to the first and second regionson the substrate at either the same or different concentrations.Moreover, within a given predefined region on the substrate, thecomponent can be delivered in either a uniform or gradient fashion. Ifthe same components are delivered to the first and second regions of thesubstrate at identical concentrations, then the reaction conditions(e.g., reaction temperatures, reaction times, etc.) under which thereactions are carried out can be varied from reaction region to reactionregion.

Moreover, in one embodiment of the present invention, a method isprovided for forming at least two different arrays of materials bydelivering substantially the same reactant components at substantiallyidentical concentrations to reaction regions on both first and secondsubstrates and, thereafter, subjecting the components on the firstsubstrate to a first set of reaction conditions and the components onthe second substrate to a second set of reaction conditions in a widearray of compositions. Using this method, the effects of the variousreaction parameters can be studied and, in turn, optimized. Reactionparameters which can be varied include, for example, reactant amounts,reactant solvents, reaction temperatures, reaction times, the pressuresat which the reactions are carried out, the atmospheres in which thereactions are conducted, the rates at which the reactions are quenched,the order in which the reactants are deposited, etc. Other reactionparameters which can be varied will be apparent to those of skill in theart.

The reactant components in the individual reaction regions must often beprevented from moving to adjacent reaction regions. Most simply, thiscan be ensured by leaving a sufficient amount of space between theregions on the substrate so that the various components cannotinterdiffuse between reaction regions. Moreover, this can be ensured byproviding an appropriate barrier between the various reaction regions onthe substrate. In one approach, a mechanical device or physicalstructure defines the various regions on the substrate. A wall or otherphysical barrier, for example, can be used to prevent the reactantcomponents in the individual reaction regions from moving to adjacentreaction regions. This wall or physical barrier may be removed after thesynthesis is carried out. One of skill in the art will appreciate that,at times, it may be beneficial to remove the wall or physical barrierbefore screening the array of materials.

In another approach, a hydrophobic material, for example, can be used tocoat the region surrounding the individual reaction regions. Suchmaterials prevent aqueous (and certain other polar) solutions frommoving to adjacent reaction regions on the substrate. Of course, whennon-aqueous or nonpolar solvents are employed, different surfacecoatings will be required. Moreover, by choosing appropriate materials(e.g., substrate material, hydrophobic coatings, reactant solvents,etc.), one can control the contact angle of the droplet with respect tothe substrate surface. Large contact angles are desired because the areasurrounding the reaction region remains unwetted by the solution withinthe reaction region.

In the delivery systems of the present invention, a small, preciselymetered amount of each reactant component is delivered into eachreaction region. This may be accomplished using a variety of deliverytechniques, either alone or in combination with a variety of maskingtechniques. For example, thin-film deposition techniques in combinationwith physical masking or photolithographic techniques can be used todeliver the various reactants to selected regions on the substrate. Moreparticularly, sputtering systems, spraying techniques, laser ablationtechniques, electron beam or thermal evaporation, ion implantation ordoping techniques, chemical vapor deposition (CVD), as well as othertechniques used in the fabrication of integrated circuits and epitaxallygrown materials can be applied to deposit highly uniform layers of thevarious reactants on selected regions of the substrate. Alternatively,by varying the relative geometries of the mask, target and/or substrate,a gradient of components can be deposited within each predefined regionson the substrate or, alternatively, over all of the predefined regionson the substrate. Such thin-film deposition techniques are generallyused in combination with masking techniques to ensure that the reactantcomponents are being delivered only to the reaction regions of interest.

Moreover, in addition to the foregoing, the various reactant componentscan be deposited into the reaction regions of interest from a dispenserin the form of droplets or powder. Conventional micropipetting apparatuscan, for example, be adapted to dispense droplet volumes of 5 nanolitersor smaller from a capillary. Such droplets can fit within a reactionregion having a diameter of 300 μm or less when a mask is employed. Thedispenser can also be of the type employed in conventional ink-jetprinters. Such ink-jet dispenser systems include, for example, the pulsepressure type dispenser system, the bubble jet type dispenser system andthe slit jet type dispenser system. These ink-jet dispenser systems areable to deliver droplet volumes as small as 5 picoliters. Moreover, suchdispenser systems can be manual or, alternatively, they can be automatedusing, for example, robotics techniques.

The dispenser of the present invention can be aligned with respect tothe appropriate reaction regions by a variety of conventional systems.Such systems, which are widely used in the microelectronic devicefabrication and testing arts, can deliver droplets to individualreaction regions at rates of up to 5,000 drops per second. Thetranslational (X-Y) accuracy of such systems is well within 1 μm. Theposition of the dispenser stage of such systems can be calibrated withrespect to the position of the substrate by a variety of methods knownin the art. For example, with only one or two reference points on thesubstrate surface, a “dead reckoning” method can be provided to locateeach reaction region of the array. The reference marks in any suchsystems can be accurately identified by using capacitive, resistive oroptical sensors. Alternatively, a “vision” system employing a camera canbe employed.

In another embodiment of the present invention, the dispenser can bealigned with respect to the reaction region of interest by a systemanalogous to that employed in magnetic and optical storage media fields.For example, the reaction region in which the component is to bedeposited is identified by its track and sector location on the disk.The dispenser is then moved to the appropriate track while the disksubstrate rotates. When the appropriate reaction region is positionedbelow the dispenser, a droplet of reactant solution is released.

In some embodiments, the reaction regions may be further defined bydimples in the substrate surface. This will be especially advantageouswhen a head or other sensing device must contact or glide along thesubstrate surface. The dimples may also act as identification marksdirecting the dispenser to the reaction region of interest.

III. Isolation of Reaction Regions on a Substrate

In a preferred embodiment, the methods of the present invention are usedto prepare an array of diverse materials at known locations on a singlesubstrate surface. Essentially, any conceivable substrate can beemployed in the invention. The substrate can be organic, inorganic,biological, nonbiological, or a combination of any of these, existing asparticles, strands, precipitates, gels, sheets, tubing, spheres,containers, capillaries, pads, slices, films, plates, slides, etc. Thesubstrate can have any convenient shape, such a disc, square, sphere,circle, etc. The substrate is preferably flat, but may take on a varietyof alternative surface configurations. For example, the substrate maycontain raised or depressed regions on which the synthesis of diversematerials takes place. The substrate and its surface preferably form arigid support on which to carry out the reaction described herein. Thesubstrate may be any of a wide variety of materials including, forexample, polymers, plastics, pyrex, quartz, resins, silicon, silica orsilica-based materials, carbon, metals, inorganic glasses, inorganiccrystals, membranes, etc. Other substrate materials will be readilyapparent to those of skill in the art upon review of this disclosure.Surfaces on the solid substrate can be composed of the same materials asthe substrate or, alternatively, they can be different, i.e., thesubstrates can be coated with a different material. Moreover, thesubstrate surface can contain thereon an adsorbent (for example,cellulose) to which the components of interest are delivered. The mostappropriate substrate and substrate-surface materials will depend on theclass of materials to be synthesized and the selection in any given casewill be readily apparent to those of skill in the art.

In some embodiments, a predefined region on the substrate and,therefore, the area upon which each distinct material is synthesized issmaller than about 25 cm², preferably less than 10 cm², more preferablyless than 5 cm², even more preferably 1 cm², still more preferably lessthan 1 mm², and still more preferably less than 0.5 mm². In mostpreferred embodiments, the regions have an area less than about 10,000μm², preferably less than 1,000 μm², more preferably less than 100 μm²,and even more preferably less than 10 μm².

In preferred embodiments, a single substrate has at least 10 differentmaterials and, more preferably, at least 100 different materialssynthesized thereon. In even more preferred embodiments, a singlesubstrate has more than 10³, 10⁴, 10⁵, 10⁶, or more materialssynthesized thereon. In some embodiments, the delivery process isrepeated to provide materials with as few as two components, althoughthe process may be readily adapted to form materials having 3, 4, 5, 6,7, 8 or more components therein. The density of regions per unit areawill be greater than 0.04 regions/cm², more preferably greater than 0.1regions/cm², even more preferably greater than 1 region/cm², even morepreferably greater than 10 regions/cm², and still more preferablygreater than 100 regions/cm². In most preferred embodiments, the densityof regions per unit area will be greater than 1,000 regions/cm², morepreferably 10,000 regions/cm², even more preferably greater than 100,000regions/cm², and still more preferably 10,000,000 regions/cm².

In other embodiments, the substrate can be a series of small beads orpellets (hereinafter “beads”). The number of beads used will depend onthe number of materials to be synthesized and can range anywhere from 2to an infinite number of beads. In this embodiment, each of the beads isuniformly coated with the reactant component(s) of interest and,thereafter, reacted. This is readily done, for example, by using aseries of vessels each of which contains a solution of a particularreactant component. The beads are equally divided into groupscorresponding to the number of components used to generate the array ofmaterials. Each group of beads is then added to one of the vesselswherein a coating of one of the components in solution forms on thesurface of each bead. The beads are then pooled together into one groupand heated to produce a dry component layer on the surface of each ofthe beads. The process is repeated several times to generate an array ofdifferent reaction components on each of the beads. Once the componentsof interest have been deposited on the beads, the beads are reacted toform an array of materials. All of the beads may or may not be reactedunder the same reaction conditions. To determine the history of thecomponents deposited on a particular bead, mass spectroscopic techniquescan be used. Alternatively, each bead can have a tag which indicates thehistory of components deposited thereon as well as theirstoichiometries. The tag can be, for example, a binary tag etched intothe surface of the bead so that it can be read using spectroscopictechniques. As with the single substrate having an array of materialsthereon, each of the individual beads or pellets can be screened formaterials having useful properties.

More particularly, if an array of materials is to be generated based onBi, Cu, Ca and Si using a series of beads as the substrate, for example,four vessels containing aqueous solutions of Bi(NO₃)₃, Cu(NO₃)₃,Ca(NO₃)₃ and Si(NO₃)₃ would be employed. A portion of the beads areadded to the vessel containing the Bi(NO₃)₃ solution; a portion of thebeads are added to the Cu(NO₃)₃ solution; a portion of the beads areadded to the vessel containing the Ca(NO₃)₃ solution; and, finally, aportion of the beads are added to the vessel containing the Si(NO₃)₃solution. Once the beads are uniformly coated with the componentcontained in the vessel, the beads are removed from the vessel, dried,etched, pooled together into one group and, thereafter, subsequentlydivided and added to the vessels containing the foregoing reactantcomponents of interest. The process is optionally repeated, withadditional components, to form a vast array of components on each of thebeads. It will be readily apparent to those of skill in the art that anumber of variations can be made to this technique to generate a vastarray of beads containing a vast array of components thereon. Forexample, some of the beads can be coated with only two components,others with more than two components. Additionally, some of the beadscan be coated two or more times with the same components, whereas otherbeads are coated a single time with a given component.

As previously explained, the substrate is preferably flat, but may takeon a variety of alternative surface configurations. Regardless of theconfiguration of the substrate surface, it is imperative that thereactant components in the individual reaction regions be prevented frommoving to adjacent reaction regions. Most simply, this can be ensured byleaving a sufficient amount of space between the regions on thesubstrate so that the various components cannot interdiffuse betweenreaction regions. Moreover, this can be ensured by providing anappropriate barrier between the various reaction regions on thesubstrate. A mechanical device or physical structure can be used todefine the various regions on the substrate. For example, a wall orother physical barrier can be used to prevent the reactant components inthe individual reaction regions from moving to adjacent reactionregions. Alternatively, a dimple or other recess can be used to preventthe reactant components in the individual reaction regions from movingto adjacent reaction regions.

If the substrate used in the present invention is to contain dimples orother recesses, the dimples must be sufficiently small to allow closepacking on the substrate. Preferably, the dimples will be less than 1 mmin diameter, preferably less than 0.5 mm in diameter, more preferablyless than 10,000 μm in diameter, even more preferably less than 100 μmin diameter, and still more preferably less than 25 μm in diameter. Thedepth of such dimples will preferably be less than 100 μm and morepreferably less than 25 μm below the upper surface of the substrate.

Dimples having these characteristics can be produced by a variety oftechniques including laser, pressing, or etching techniques. A suitabledimpled substrate surface can, for example, be provided by pressing thesubstrate with an imprinted “master” such as those commonly used toprepare compact optical disks. In addition, an isotropic or anisotropicetching technique employing photolithography can be employed. In suchtechniques, a mask is used to define the reaction regions on thesubstrate. After the substrate is irradiated through the mask, selectedregions of the photoresist are removed to define the arrangement ofreaction regions on the substrate. The dimples may be cut into thesubstrate with standard plasma or wet etching techniques. If thesubstrate is a glass or silicon material, suitable wet etch materialscan include hydrogen fluoride, or other common wet etchants used in thefield of semiconductor device fabrication. Suitable plasma etchantscommonly used in the semiconductor device fabrication field can also beemployed. Such plasma etchants include, for example, mixtures of halogencontaining gases and inert gases. Typically, a plasma etch will producedimples having a depth of less than 10 μm, although depths of up to 50μm may be obtained under some conditions.

Another method for preparing a suitably dimpled surface employsphotochemically etchable glass or polymer sheets. For example, aphotochemically etchable glass known as “FOTOFORM” is available fromCorning Glass Company (New York). Upon exposure to radiation through amask, the glass becomes soluble in aqueous solutions. Thereafter, theexposed glass is simply washed with the appropriate solution to form thedimpled surface. With this material, well-defined dimples can be madehaving aspect ratios of 10 to 1 (depth to diameter) or greater, anddepths of up to 0.1 inches. Dimple diameters can be made as small as 25μm in a 250 μm thick glass layer. Moreover, the dimpled surface cancontain thereon an adsorbent (for example, cellulose) to which thecomponents of interest are delivered.

Even when a dimpled surface is employed, it is often important to ensurethat the substrate material is not wetted beyond the reaction regionparameters. Most simply, this can be ensured by leaving a sufficientamount of space between the regions on the substrate so that the variouscomponents cannot interdiffuse between reaction regions. In addition,other techniques can be applied to control the physical interactionsthat affect wetting, thereby ensuring that the solutions in theindividual reaction regions do not wet the surrounding surface andcontaminate other reaction regions. Whether or not a liquid droplet willwet a solid surface is governed by three tensions: the surface tensionat the liquid-air interface, the interfacial tension at the solid-liquidinterface and the surface tension at the solid-air interface. If the sumof the liquid-air and liquid-solid tensions is greater than thesolid-air tension, the liquid drop will form a bead (a phenomenon knownas “lensing”). If, on the other hand, the sum of the liquid-air andliquid-solid tensions is less than the solid-air tension, the drop willnot be confined to a given location, but will instead spread over thesurface. Even if the surface tensions are such that the drop will notspread over the surface, the contact or wetting angle (i.e., the anglebetween the edge of the drop and the solid substrate) may besufficiently small that the drop will cover a relatively large area(possibly extending beyond the confines of a given reaction region).Further, small wetting angles can lead to formation of a thin(approximately 10 to 20 Å) “precursor film” which spreads away from theliquid bead. Larger wetting angles provide “taller” beads that take upless surface area on the substrate and do not form precursor films.Specifically, if the wetting angle is greater than about 90°, aprecursor film will not form.

Methods for controlling chemical compositions and, in turn, the localsurface free energy of a substrate surface include a variety oftechniques apparent to those in the art. Chemical vapor deposition andother techniques applied in the fabrication of integrated circuits canbe applied to deposit highly uniform layers on selected regions of thesubstrate surface. If, for example, an aqueous reactant solution isused, the region inside the reaction regions may be hydrophilic, whilethe region surrounding the reaction regions may be hydrophobic. As such,the surface chemistry can be varied from position to position on thesubstrate to control the surface free energy and, in turn, the contactangle of the drops of reactant solution. In this manner, an array ofreaction regions can be defined on the substrate surface.

Moreover, as previously explained, the reactant components in theindividual reaction regions can be prevented from moving to adjacentreaction regions by leaving a sufficient amount of space between theregions on the substrate so that the various components cannotinterdiffuse between reaction regions.

IV. Methods for Delivery of Reactant Components

In the delivery systems of the present invention, a small, preciselymetered amount of each reactant component is delivered into eachreaction region. This may be accomplished using a variety of deliverytechniques, either alone or in combination with a variety of physicalmasking or photolithographic techniques. Delivery techniques which aresuitable for use in the methods of the present invention can generallybe broken down into those involving the use of thin-film depositiontechniques and those involving the use of a dispenser.

A. Delivery Using Thin-Film Deposition Techniques

Thin-film deposition techniques in combination with physical masking orphotolithographic techniques can be used to deposit thin-films of thevarious reactants on predefined regions on the substrate. Such thin-filmdeposition techniques can generally be broken down into the followingfour categories: evaporative methods, glow-discharge processes,gas-phase chemical processes, and liquid-phase chemical techniques.Included within these categories are, for example, sputteringtechniques, spraying techniques, laser ablation techniques, electronbeam or thermal evaporation techniques, ion implantation or dopingtechniques, chemical vapor deposition techniques, as well as othertechniques used in the fabrication of integrated circuits. All of thesetechniques can be applied to deposit highly uniform layers, i.e.,thin-films, of the various reactants on selected regions on thesubstrate. Moreover, by adjusting the relative geometries of the masks,the delivery source and/or the substrate, such thin-film depositiontechniques can be used to generate uniform gradients at each reactionregion on the substrate or, alternatively, over all of the reactionregions on the substrate. For an overview of the various thin-filmdeposition techniques which can be used in the methods of the presentinvention, see, for example, Handbook of Thin-Film Deposition Processesand Techniques, Noyes Publication (1988), which is incorporated hereinby reference for all purposes.

Thin-films of the various reactants can be deposited on the substrateusing evaporative methods in combination with physical maskingtechniques. Generally, in thermal evaporation or vacuum evaporationmethods, the following sequential steps take place: (1) a vapor isgenerated by boiling or subliming a target material; (2) the vapor istransported from the source to the substrate; and (3) the vapor iscondensed to a solid film on the substrate surface. Evaporants, i.e.,target materials, which can be used in the evaporative methods cover anextraordinary range of varying chemical reactivity and vapor pressuresand, thus, a wide variety of sources can be used to vaporize the targetmaterial. Such sources include, for example, resistance-heatedfilaments, electron beams; crucible heated by conduction, radiation orrf-inductions; arcs, exploding wires and lasers. In preferredembodiments of the present invention, thin-film deposition usingevaporative methods is carried out using lasers, filaments, electronbeams or ion beams as the source. Successive rounds of deposition,through different physical masks, using evaporative methods generates anarray of reactants on the substrate for parallel synthesis.

Molecular Beam Epitaxy (MBE) is an evaporative method that can be usedto grow epitaxial thin-films. In this method, the films are formed onsingle-crystal substrates by slowly evaporating the elemental ormolecular constituents of the film from separate Knudsen effusion sourcecells (deep crucibles in furnaces with cooled shrouds) onto substratesheld at temperatures appropriate for chemical reaction, epitaxy andre-evaporation of excess reactants. The furnaces produce atomic ormolecular beams of relatively small diameter, which are directed at theheated substrate, usually silicon or gallium arsenide. Fast shutters areinterposed between the sources and the substrates. By controlling theseshutters, one can grow superlattices with precisely controlleduniformity, lattice match, composition, dopant concentrations, thicknessand interfaces down to the level of atomic layers.

In addition to evaporative methods, thin-films of the various reactantscan be deposited on the substrate using glow-discharge processes incombination with physical masking techniques. The most basic and wellknown of these processes is sputtering, i.e., the ejection of surfaceatoms from an electrode surface by momentum transfer from bombardingions to surface atoms. Sputtering or sputter-deposition is a term usedby those of skill in the art to cover a variety of processes. One suchprocess is RF/DC Glow Discharge Plasma Sputtering. In this process, aplasma of energized ions is created by applying a high RF or DC voltagebetween a cathode and an anode. The energized ions from the plasmabombard the target and eject atoms which then deposit on a substrate.Ion-Beam Sputtering is another example of a sputtering process which canbe used to deposit thin-films of the various reactant components on thesubstrate. Ion-Beam Sputtering is similar to the foregoing processexcept the ions are supplied by an ion source and not a plasma. It willbe apparent to one of skill in the art that other sputtering techniques(e.g., diode sputtering, reactive sputtering, etc.) and otherglow-discharge processes can be used to deposit thin-films on asubstrate. Successive rounds of deposition, through different physicalmasks, using sputtering or other glow-discharge techniques generates anarray of reactants on the substrate for parallel synthesis.

An example of an eight RF magnetron sputtering gun system which can beemployed in the methods of the present invention is illustrated in FIG.1. This system comprises eight RF magnetron sputtering guns 110, each ofwhich contains a reactant component of interest. The eight RF magnetronsputtering guns are located about 3 to about 4 inches above a disk 112containing thereon eight masking patterns 114 as well as eightfilm-thickness monitors 116. In this system, the eight RF magnetronsputtering guns as well as the disk are fixed. The substrate 118,however, is coupled to a substrate manipulator 120 which is capable oflinear and rotational motion and which engages the substrate with theparticular mask of interest so that the substrate is in contact with themask when the sputtering begins. Combinations of the eight componentsare generated on the substrate by the sequential deposition of eachcomponent through its respective mask. This entire system is used invacuo.

In addition to evaporative methods and sputtering techniques, thin-filmsof the various reactants can be deposited on the substrate usingChemical Vapor Deposition (CVD) techniques in combination with physicalmasking techniques. CVD involves the formation of stable solids bydecomposition of gaseous chemicals using heat, plasma, ultraviolet, orother energy source, of a combination of sources. Photo-Enhanced CVD,based on activation of the reactants in the gas or vapor phase byelectromagnetic radiation, usually short-wave ultraviolet radiation, andPlasma-Assisted CVD, based on activation of the reactants in the gas orvapor phase using a plasma, are two particularly useful chemical vapordeposition techniques. Successive rounds of deposition, throughdifferent physical masks, using CVD techniques generates an array ofreactants on the substrate for parallel synthesis.

In addition to evaporative methods, sputtering and CVD, thin-films ofthe various reactants can be deposited on the substrate using a numberof different mechanical techniques in combination with physical maskingtechniques. Such mechanical techniques include, for example, spraying,spinning, dipping, and draining, flow coating, roller coating,pressure-curtain coating, brushing, etc. Of these, the spray-on andspin-on techniques are particularly useful. Sprayers which can be usedto deposit thin-films include, for example, ultrasonic nozzle sprayers,air atomizing nozzle sprayers and atomizing nozzle sprayers. Inultrasonic sprayers, disc-shaped ceramic piezoelectric transducerscovert electrical energy into mechanical energy. The transducers receiveelectrical input in the form of a high-frequency signal from a powersupply that acts as a combination oscillator/amplifier. In air atomizingsprayers, the nozzles intermix air and liquid streams to produce acompletely atomized spray. In atomizing sprayers, the nozzles use theenergy of from a pressurized liquid to atomize the liquid and, in turn,produce a spray. Successive rounds of deposition, through differentphysical masks, using mechanical techniques such as spraying generatesan array of reactants on the substrate for parallel synthesis.

In addition to the foregoing techniques, photolithographic techniques ofthe type known in the semiconductor industry can be used. For anoverview of such techniques, see, for example, Sze, VLSI Technology,McGraw-Hill (1983) and Mead, et al., Introduction to VLSI Systems,Addison-Wesley (1980), which are incorporated herein by reference forall purposes. A number of different photolithographic techniques knownto those of skill in the art can be used. In one embodiment, forexample, a photoresist is deposited on the substrate surface; thephotoresist is selectively exposed, i.e., photolyzed; the photolyzed orexposed photoresist is removed; a reactant is deposited on the exposedregions on the substrate; and the remaining unphotolyzed photoresist isremoved. Alternatively, when a negative photoresist is used, thephotoresist is deposited on the substrate surface; the photoresist isselectively exposed, i.e., photolyzed; the unphotolyzed photoresist isremoved; a reactant is deposited on the exposed regions on thesubstrate; and the remaining photoresist is removed. In anotherembodiment, a reactant is deposited on the substrate using, for example,spin-on or spin-coating techniques; a photoresist is deposited on top ofthe reactant; the photoresist is selectively exposed, i.e., photolyzed;the photoresist is removed from the exposed regions; the exposed regionsare etched to remove the reactant from those regions; and the remainingunphotolyzed photoresist is removed. As with the previous embodiment, anegative photoresist can be used in place of the positive photoresist.Such photolithographic techniques can be repeated to produce an array ofreactants on the substrate for parallel synthesis.

Using the foregoing thin-film deposition techniques in combination withphysical masking or photolithographic techniques, a reactant componentcan be delivered to all of the predefined regions on the substrate in auniform distribution (i.e., in the stoichiometry at each predefinedregion) or, alternatively, in a gradient of stoichiometries. Moreover,multiple reactant components can be delivered to all of the predefinedregions on the substrate in a gradient of stoichiometries. For example,a first component can be deposited through a 100-hole mask from left toright as a gradient layer ranging from about 100 Å to about 1,000 Å inthickness. Thereafter, a second component can be deposited through a100-hole mask from top to bottom as a gradient layer ranging from about200 Å to about 2,000 Å in thickness. Once the components have beendelivered to the substrate, the substrate will contain 100 predefinedregions with varying ratios of the two components in each of thepredefined regions. In addition, using the foregoing thin-filmdeposition techniques in combination with physical masking techniques, areactant component can be delivered to a particular predefined region onthe substrate in a uniform distribution or, alternatively, in a gradientof stoichiometries.

It will be readily apparent to those of skill in the art that theforegoing deposition techniques are intended to illustrate, and notrestrict, the ways in which the reactants can be deposited on thesubstrate in the form of thin-films. Other deposition techniques knownto and used by those of skill in the art can also be used.

FIG. 2 and FIG. 3 illustrate the use of the physical masking techniqueswhich can be used in conjunctions with the aforementioned thin-filmdeposition techniques. More particularly, FIG. 2 illustrates oneembodiment of the invention disclosed herein in which a substrate 2 isshown in cross-section. The mask 8 can be any of a wide variety ofdifferent materials including, for example, polymers, plastics, resins,silicon, metals, inorganic glasses, etc. Other suitable mask materialswill be readily apparent to those of skill in the art. The mask isbrought into close proximity with, imaged on, or brought directly intocontact with the substrate surface as shown in FIG. 2. “Openings” in themask correspond to regions on the substrate where it is desired todeliver a reactant. Conventional binary masking techniques in whichone-half of the mask is exposed at a given time are illustratedhereinbelow. It will be readily apparent to those of skill in the art,however, that masking techniques other than conventional binary maskingtechniques can be used in the methods of the present invention.

As shown in FIG. 3A, the substrate 2 is provided with regions 22, 24,26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50 and 52. Regions 38,40, 42, 44, 46, 48, 50 and 52 are masked, as shown in FIG. 3B, andcomponent A is delivered to the exposed regions in the form of athin-film using, for example, spraying or sputtering techniques, withthe resulting structure shown in FIG. 3C. Thereafter, the mask isrepositioned so that regions 26, 28, 34, 36, 42, 44, 50 and 52 aremasked, as shown in FIG. 3D, and component B is delivered to the exposedregions in the form of a thin-film, with the resulting structure shownin FIG. 3E.

As an alternative to repositioning the first mask, a second mask can beused and, in fact, multiple masks are frequently required to generatethe desired array of reactants. If multiple masking steps are used,alignment of the masks may be performed using conventional alignmenttechniques in which alignment marks (not shown) are used to accuratelyoverly successive masks with previous patterning steps, or moresophisticated techniques can be used. Moreover, it may be desirable toprovide separation between exposed areas to account for alignmenttolerances and to ensure separation of reaction sites so as to preventcross-contamination. In addition, it will be understood by those ofskill in the art that the delivery techniques used to deliver thevarious reactants to the regions of interest can be varied from reactantto reactant, but, in most instances, it will be most practical to usethe same deposition technique for each of the reactants.

After component B has been delivered to the substrate, regions 30, 32,34, 36, 46, 48, 50 and 52 are masked, as shown in FIG. 3F, using a maskdifferent from that used in the delivery of components A and B.Component C is delivered to the exposed regions in the form of athin-film, with the resulting structure shown in FIG. 3G. Thereafter,regions 24, 28, 32, 36, 40, 44, 48 and 52 are masked, as shown in FIG.3H, and component D is delivered to the exposed regions in the form of athin-film, with the resulting structure shown in FIG. 3I. Once thecomponents of interest have been delivered to appropriate predefinedregions on the substrate, they are simultaneously reacted using any of anumber of different synthetic routes to form an array of at least twomaterials.

As previously mentioned, masking techniques other than conventionalbinary masking techniques can be employed with the aforementionedthin-film deposition techniques in the methods of the present invention.For example, FIG. 4 illustrates a masking technique which can beemployed to generate an array of materials, each consisting of acombination of three different components, formed from a base group offour different components. In non-conventional binary techniques, aseparate mask is employed for each of the different components. Thus, inthis example, four different masks are employed. As shown in FIG. 4A,the substrate 2 is provided with regions 54, 56, 58 and 60. Region 56 ismasked, as shown in FIG. 4B, and component A is delivered to the exposedregions in the form of a thin-film using, for example, spraying orsputtering techniques, with the resulting structure shown in FIG. 4C.Thereafter, a second mask is employed to mask region 54, as shown inFIG. 4D, and component B is delivered to the exposed regions in the formof a thin-film, with the resulting structure shown in FIG. 4E.Thereafter, region 58 is masked using a third mask, as shown in FIG. 4F,and component C is delivered to the exposed regions in the form of athin-film, with the resulting structure shown in FIG. 4G. Finally, afourth mask is employed to mask region 60, as shown in FIG. 4H, andcomponent D is delivered to the exposed regions in the form of athin-film, with the resulting structure shown in FIG. 4I. Once thecomponents of interest have been delivered to appropriate predefinedregions on the substrate, they are simultaneously reacted using any of anumber of different synthetic routes to form an array of four differentmaterials.

FIG. 5 illustrates another masking technique which can be employed togenerate an array of materials, each consisting of a combination ofthree different components, formed from a base group of six differentcomponents. As shown in FIG. 5A, the substrate 2 is provided withregions 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92,94, 96, 98 and 100. Regions 64, 68, 72, 76, 80, 84, 88, 92, 96 and 100are masked, as shown in FIG. 5B, and component A is delivered to theexposed regions in the form of a thin-film using, for example, sprayingor sputtering techniques, with the resulting structure shown in FIG. 5C.Thereafter, a second mask is employed to mask regions 62, 66, 72, 74,80, 82, 88, 90, 96 and 98, as shown in FIG. 5D, and component B isdelivered to the exposed regions in the form of a thin-film, with theresulting structure shown in FIG. 5E. Thereafter, regions 64, 66, 70,74, 78, 82, 86, 92, 96, and 100 are masked using a third mask, as shownin FIG. 5F, and component C is delivered to the exposed regions in theform of a thin-film, with the resulting structure shown in FIG. 5G.Thereafter, a fourth mask is employed to mask regions 64, 66, 70, 76,78, 84, 88, 90, 94 and 98, as shown in FIG. 5H, and component D isdelivered to the exposed regions in the form of a thin-film, with theresulting structure shown in FIG. 5I. Thereafter, regions 62, 68, 70,74, 80, 84, 86, 90, 94 and 100 are masked with a fifth mask, as shown inFIG. 5J, and component E is delivered to the exposed regions in the formof a thin-film, with the resulting structure shown in FIG. 5K. Finally,a sixth mask is employed to mask regions 62, 68, 72, 76, 78, 82, 86, 92,94 and 98, as shown in FIG. 5L, and component F is delivered to theexposed regions in the form of a thin-film, with the resulting structureshown in FIG. 5M. Once the components of interest have been delivered toappropriate predefined regions on the substrate, they are simultaneouslyreacted using any of a number of different synthetic routes to form anarray of 20 different materials.

It will be readily apparent to those of skill in the art thatalternative masking techniques can be employed to generate an array ofmaterials, each consisting of a combination of 3 or more components,formed from a base group of four or more components.

B. Delivery Using A Dispenser

In addition to the foregoing delivery techniques, dispensers can beutilized to generate diverse combinations of reactant components in theform of droplets or powder on a single substrate. As explained above,commercially available micropipetting apparatus can be adapted todispense droplet volumes of 5 nanoliters or smaller from a capillary.Such droplets can fit within a reaction region having a diameter of 300μm or less when a non-wetting mask is employed. In some embodiments, themicropipette is accurately and precisely positioned above the reaction,as described below, before the reactant solution is deposited.

In a different preferred embodiment, the present invention employs asolution depositing apparatus that resembles devices commonly employedin the ink-jet printing field. Such ink-jet dispensers include, forexample, the pulse pressure type, the bubble jet type and the slit jettype. In an ink-jet dispenser of the pulse pressure type, the printingink is jetted from a nozzle according to a change in pressure applied bya piezoelectric device. In an ink-jet dispenser of the bubble jet type,bubbles are generated with heat generated with a resistance deviceembedded in a nozzle, and printing ink is jetted by using the force dueto the expansion of a bubble. In an ink-jet dispenser of the slit jettype, printing ink is filled within a slit-like orifice whereinrecording electrodes are aligned in correspondence to pixels, and a DCvoltage pulse is applied between a recording electrode and a counterelectrode arranged behind a recording paper. In this system, theprinting ink around the top of the record electrode is chargedelectrically so that the ink is ejected towards the recording paper withan electrostatic force to record a dot on the paper.

Such ink-jet printers can be used with minor modification by simplysubstituting a reactant containing solution or reactant containingpowder for the ink. For example, Wong, et al., European PatentApplication 260 965, incorporated herein by reference for all purposes,describes the use of a pulse pressure type inkjet printer to apply anantibody to a solid matrix. In the process, a solution containing theantibody is forced through a small bore nozzle that is vibrating in amanner that fragments the solution into discrete droplets. The dropletsare subsequently charged by passing through an electric field and thendeflected onto the matrix material.

For illustrative purposes, a conventional ink drop printer of the pulsepressure type includes a reservoir in which ink is held under pressure.The ink reservoir feeds a pipe which is connected to a nozzle. Anelectromechanical transducer is employed to vibrate the nozzle at somesuitable high frequency. The actual structure of the nozzle may have anumber of different constructions, including a drawn glass tube which isvibrated by an external transducer, or a metal tube vibrated by anexternal transducer (e.g., a piezoelectric crystal), or amagnetostrictive metal tube which is magnetostrictively vibrated. Theink accordingly is ejected from the nozzle in a stream which shortlythereafter breaks into individual drops. An electrode may be presentnear the nozzle to impart a charge to the droplets.

A schematic drawing of an ink drop dispenser of the pulse pressure type(such as is described in U.S. Pat. Nos. 3,281,860 and 4,121,222, whichare incorporated by reference herein for all purposes) which may beemployed in the present invention is shown in FIG. 6. This apparatuscomprises a reservoir 210 which contains a solution under pressure.Tubing 212 is connected to the reservoir 210 and terminates in a metalnozzle 242. Nozzle 242 is disposed within a hole provided inpiezoelectric crystal 240. The end of the metal tube and of thepiezoelectric crystal are made to coincide. The tubing and thepiezoelectric crystal are soldered together to form a permanentwaterproof attachment. The coincident ends of the crystal and the tubingare covered with a washer 244 which is termed an orifice washer. Thiswasher has an opening 246 drilled therethrough through which thesolution is emitted under pressure. A source of oscillations 218 isconnected between the outside of the metal tubing 242 and the outside ofthe piezoelectric crystal 240. The construction is such that hermeticsealing can be employed which protects against electrochemical andatmospheric attack of the components.

The piezoelectric crystal 240 is vibrated substantially at the frequencyof the source of oscillations causing the tubing and nozzle to vibratewhereby the solution stream breaks down into droplets 246. A signalsource 224 which is synchronized by the source of oscillations isconnected between the nozzle and the charging cylinder 226. As a result,each of the drops, which should be substantially the same mass, receivesa charge, the amplitude of which is determined by the amplitude of thesignal applied from the source 224 and the charging cylinder 226.

The charged drops, after passing through the charging cylinder, passinto an electric field which is established between two platesrespectively 230 and 232 which are connected to a field potential source234. As a result of the action between the field and the charge of eachdrop, the drops are deflected from their center line path between theplates in accordance with the charge which they carry. Thus, when theyfall on an optionally moving writing medium 236, a deposition patternoccurs on the writing medium representative of the information in thesignals.

Although the ink-jet printer of the pulse pressure type has beendescribed in greater detail herein for purposes of illustration, it willbe readily apparent to those of skill in the art that ink-jet printersof the bubble jet type and the slit jet type can also be used, with onlyminor modifications, to deliver reactant components to predefinedregions on the substrate. Moreover, although the foregoing discussionrefers to a single nozzle, it will be readily apparent to those of skillin the art that ink-jet printers having multiple nozzles can be used todeliver multiple reactant components to a single predefined region onthe substrate or, alternatively, to multiple predefined regions on thesubstrate. In addition, as improvements are made in field of ink-jetprinters, such improvements can be used in the methods of the presentinvention.

In other embodiments, the reactant solutions can be delivered from areservoir to the substrate by an electrophoretic pump. In such a device,a thin capillary connects a reservoir of the reactant with the nozzle ofthe dispenser. At both ends of the capillary, electrodes are present toprovide a potential difference. As is known in the art, the speed atwhich a chemical species travels in a potential gradient of anelectrophoretic medium is governed by a variety of physical properties,including the charge density, size, and shape of the species beingtransported, as well as the physical and chemical properties of thetransport medium itself. Under the proper conditions of potentialgradient, capillary dimensions, and transport medium rheology, ahydrodynamic flow will be set up within the capillary. Thus, bulk fluidcontaining the reactant of interest can be pumped from a reservoir tothe substrate. By adjusting the appropriate position of the substratewith respect to the electrophoretic pump nozzle, the reactant solutioncan be precisely delivered to predefined reaction regions.

Using the aforementioned dispenser systems, the reactants can bedelivered to predefined regions on the substrate either sequentially orsimultaneously. In a presently preferred embodiment, the reactants aresimultaneously delivered to either a single predefined region on thesubstrate or, alternatively, to multiple predefined regions on thesubstrate. For example, using an ink-jet dispenser having two nozzles,two different reactants can be simultaneously delivered to a singlepredefined region on the substrate. Alternatively, using this sameink-jet dispenser, a reactant can be simultaneously delivered to twodifferent predefined regions on the substrate. In this instance, thesame reactant or, alternatively, two different reactants can bedelivered. If the same reactant is delivered to both of the predefinedregions, it can be delivered at either the same or differentconcentrations. Similarly, using an ink-jet dispenser having eightnozzles, for example, eight different reactants can be simultaneouslydelivered to a single predefined region on the substrate or,alternatively, eight reactants (either the same or different) can besimultaneously delivered to eight different predefined regions on thesubstrate.

V. Moving the Dispenser with Respect to the Substrate

To deposit reactant droplets consistently at precisely specified regionsusing a dispenser, a frame of reference common to the deliveryinstrument and the substrate is required. In other words, the referencecoordinates of the instrument must be accurately mapped onto thereference coordinates of the substrate. Ideally, only two referencepoints on the substrate would be required to completely map the array ofreaction regions. The dispenser instrument locates these referencepoints and then adjust its internal reference coordinates to provide thenecessary mapping. After this, the dispenser can move a particulardistance in a particular direction and be positioned directly over aknown region. Of course, the dispenser instrument must provide preciselyrepeatable movements. Further, the individual regions of the array mustnot move with respect to the reference marks on the substrate after thereference marks have been formed. Unfortunately, pressing or othermechanical operations commonly encountered during fabrication and use ofa substrate can warp the substrate such that the correspondence betweenthe reference marks and the reaction regions is altered.

To allow for this possibility, a substrate containing both “global” and“local” reference marks is employed. In preferred embodiments, only twoglobal reference marks are conveniently located on the substrate todefine the initial frame of reference. When these points are located,the dispenser instrument has an approximate map of the substrate and thepredefined regions therein. To assist in locating the exact position ofthe regions, the substrate is further subdivided into local frames ofreference. Thus, in an initial, “course” adjustment, the dispenser ispositioned within one of the local frames of reference. Once in thelocal region, the dispensing instrument looks for local reference marksto define further a local frame of reference. From these, the dispensermoves exactly to the reaction region where the reactant is deposited. Inthis manner, the effects of warpage or other deformation can beminimized. The number of local reference marks is determined by theamount of deformation expected in the substrate. If the substrate issufficiently rigid so that little or no deformation will occur, very fewlocal reference marks are required. If substantial deformation isexpected, however, more local reference marks are required.

Starting at a single reference point, the micropipette or otherdispenser is translated from one reaction region to other reactionregions of the substrate by a correct distance in the correct direction(this is the “dead reckoning” navigational technique). Thus, thedispenser can move from region to region, dispensing correctly meteredamounts of reactant. In order to initially locate the reference pointand align the dispenser directly over it, a vision or blind system canbe employed. In a vision system, a camera is rigidly mounted to thedispenser nozzle. When the camera locates the reference point(s), thedispenser is known to be a fixed distance and direction away from thepoint, and a frame of reference is established. Blind systems locate thereference point(s) by capacitive, resistive, or optical techniques, forexample. In one example of an optical technique, a laser beam istransmitted through or reflected from the substrate. When the beamencounters a reference mark, a change in light intensity is detected bya sensor. Capacitive and resistive techniques are similarly applied. Asensor registers a change in capacitance or resistivity when a referencepoint is encountered.

For purposes of this invention, the spacing between the individualregions will vary in accordance with the size of the regions used. Forexample, if a 1 mm² region is used, the spacing between the individualregions will preferably be on the order of 1 mm or less. If, forexample, a 10 μm² region is used, the spacing between the individualregions will preferably be on the order of 10 μm or less. Further, theangular relation between the cells is preferably consistent, to within0.1 degrees. Of course, the photolithographic or other process used todefine the arrangement of cells will accurately define the angle andspacing. However, in subsequent processes (e.g., pressing processes),the angle can be distorted. Thus, in some embodiments, it may benecessary to employ “local” reference points throughout the array.

Translational mechanisms capable of moving with the desired precisionare preferably equipped with position feedback mechanisms (i.e.,encoders) of the type used in devices for semiconductor devicemanufacturing and testing. Such mechanisms will preferably be closedloop systems with insignificant backlash and hysteresis. In preferredembodiments, the translation mechanism will have a high resolution,i.e., greater than five motor ticks per encoder count. Further, theelectromechanical mechanism will preferably have a high repeatabilityrelative to the region diameter travel distance (preferably, ±1-5 μm).

To deposit a drop of reactant solution on the substrate accurately, thedispenser nozzle must be placed a correct distance above the surface.The dispenser tip preferably will be located about 0.1 cm to about 3 cmabove the substrate surface when the drop is released. The degree ofcontrol necessary to achieve such accuracy can be attained with arepeatable high-resolution translation mechanism of the type describedabove. In one embodiment, the height above the substrate is determinedby moving the dispenser toward the substrate in small increments, untilthe dispenser tip touches the substrate. At this point, the dispenser ismoved away from the surface a fixed number of increments whichcorresponds to a specific distance. From there, the drop is released tothe cell below. Preferably, the increments in which the dispenser moveswill vary in accordance with the size of the regions used.

In an alternative embodiment, the dispenser nozzle is encircled by asheath that rigidly extends a fixed distance beyond the dispenser tip.Preferably, this distance corresponds to the distance at which thesolution drop will fall when delivered to the selected reaction region.Thus, when the sheath contacts the substrate surface, the movement ofthe dispenser is halted and the drop is released. It is not necessary inthis embodiment to move the dispenser back, away from the substrate,after contact is made. In this embodiment, as well as the previousembodiment, the point of contact with the surface can be determined by avariety of techniques such as by monitoring the capacitance orresistance between the tip of the dispenser (or sheath) and thesubstrate below. A rapid change in either of these properties isobserved upon contact with the surface.

To this point, the dispenser delivery system has been described only interms of translational movements. However, other systems may also beemployed. In one embodiment, the dispenser is aligned with respect tothe region of interest by a system analogous to that employed inmagnetic and optical storage media fields. For example, the region inwhich reactant is to be deposited is identified by a track and sectorlocation on the disk. The dispenser is then moved to the appropriatetrack while the disk substrate rotates. When the appropriate cell ispositioned below the dispenser (as referenced by the appropriate sectoron the track), a droplet of reactant solution is released.

Control of the droplet size may be accomplished by various techniques.For example, in one embodiment, a conventional micropipetting instrumentis adapted to dispense droplets of five nanoliters or smaller from acapillary. Such droplets fit within regions having diameters of 300 μmor less when a non-wetting mask is employed.

Although the above embodiments have been directed to systems employingliquid droplets, minuscule aliquots of each test substance can also bedelivered to the reaction region as powders or miniature pellets.Pellets can be formed, for example, from the compound of interest andone or more kinds of inert binding material. The composition of suchbinders and methods for the preparation of the “pellets” will beapparent to those of skill in the art. Such “mini-pellets” will becompatible with a wide variety of test substances, stable for longperiods of time and suitable for easy withdrawal from the storage vesseland dispensing.

VI. Synthetic Routes for Reacting the Array of Components

Once the array of components have been delivered to predefined regionson the substrate, they can be simultaneously reacted using a number ofdifferent synthetic routes. The components can be reacted using, forexample, solution based synthesis techniques, photochemical techniques,polymerization techniques, template directed synthesis techniques,epitaxial growth techniques, by the sol-gel process, by thermal,infrared or microwave heating, by calcination, sintering or annealing,by hydrothermal methods, by flux methods, by crystallization throughvaporization of solvent, etc. Other useful synthesis techniques will beapparent to those of skill in the art upon review of this disclosure.Moreover, the most appropriate synthetic route will depend on the classof materials to be synthesized, and the selection in any given case willbe readily apparent to those of skill in the art. In addition, it willbe readily apparent to those of skill in the art that, if necessary, thereactant components can be mixed using, for example, ultrasonictechniques, mechanical techniques, etc. Such techniques can be applieddirectly to a given predefined region on the substrate or,alternatively, to all of the predefined regions on the substrate in asimultaneous fashion (e.g., the substrate can be mechanically moved in amanner such that the components are effectively mixed).

Traditional routes to solid-state synthesis involve the sintering ofsolid reactants. The standard method used to synthesize superconductors,for example, is to grind several metal-oxide powders together, compressthe mixture and, thereafter, bake at a temperature ranging from 800° C.to about 1000° C. The elements in the powder mixture sinter, i.e., theyreact chemically to form new compounds and fuse into a solid, withoutpassing through the liquid or gaseous phase. Gaseous elements, such asoxygen, can be taken up during sintering or, alternatively, in asubsequent step, and the pressure of the system can be varied during thesynthesis process. Unfortunately, using traditional sinteringtechniques, reaction rates are limited by the slow diffusion of atoms orions through solid reactants, intermediates and products. Moreover, hightemperatures are frequently required to accelerate diffusion and tothermodynamically drive the formation of a stable phase.

In contrast to such traditional routes, in the present invention, newroutes to solid-synthesis focus on the synthesis of compounds at lowertemperatures. It has been found that reaction rates can be increased atlower temperatures by drastically shortening the distance required fordiffusion of the reactants and by increasing the surface to volumeratio. This can be achieved by depositing the reactants on the substratein the form of very thin-films or, alternatively, by using solutionbased synthesis techniques wherein the reactants are delivered to thesubstrate in the form of a solution. Moreover, when the synthesisreaction is to be carried out at a temperature ranging from about 200°C. to about 600° C., a molten salt can be employed to dissolve thereactant components. This technique is generally referred to as the fluxmethod. Similarly, in a hydrothermal method, water or other polarsolvent containing a soluble inorganic salt is employed to dissolve thereactant components. The hydrothermal method is usually carried outunder pressure and at a temperature ranging from about 100° C. to about400° C. Moreover, using the various synthetic routes of the presentinvention, the array of reactant components can be pressurized ordepressurized under an inert atmosphere, oxygen or other gas. Inaddition, in the synthetic routes of the present invention, variousregions on the substrate can be exposed to different heat historiesusing, for example, laser thermolysis, wherein bursts of energy of apredetermined duration and intensity are delivered to target regions onthe substrate.

Furthermore, using the synthetic routes of the present invention, thearray of components can be processed between the various delivery steps.For example, component A can be delivered to a first region on asubstrate and, thereafter, exposed to oxygen at elevated temperature,for example. Subsequently, component B can be delivered to the firstregion on the substrate and, thereafter, components A and B are reactedunder a set of reaction conditions. Other manipulations and processingsteps which can be carried out between the various delivery steps willbe apparent to those of skill in the art upon reading this disclosure.

As such, using the methods of the present invention, the followingmaterials can be prepared: covalent network solids, ionic solids andmolecular solids. More particularly, the methods of the presentinvention can be used to prepare, for example, inorganic materials,intermetallic materials, metal alloys, ceramic materials, organicmaterials, organometallic materials, non-biological organic polymers,composite materials (e.g., inorganic composites, organic composites, orcombinations thereof), etc. High-temperature superconductors can beprepared, for instance, by delivering reactant components to predefinedregions on the substrate using, for example, solution based deliverytechniques. Once the reactant components of interest have been deliveredto the substrate, the substrate is heated to the boiling point of thesolvent to evaporate off the solvent. Alternatively, the solvent can beremoved by delivering the reactant components to a heated substrate. Thesubstrate is then oxidized to remove unwanted components (e.g., carbon,nitrogen, etc.) from the array. The substrate is then flash heated at atemperature of about 800° C. to about 875° C. for about two minutes.Thereafter, the reaction is rapidly quenched and the array is scannedfor materials that are superconducting. Magnetic materials can beprepared using a similar process except that in the case of magneticmaterials, the components are delivered to the substrate andsimultaneously reacted thereon in the presence of a magnetic field.

Moreover, an array of zeolites, i.e., hydrated silicates of aluminum andeither sodium, calcium or both, can be prepared using the methods of thepresent invention. To prepare an array of such materials, the reactantcomponents are delivered to predefined regions on a substrate in theform of a slurry. Using a low temperature (e.g., 60° C. to about 70° C.)hydrothermal method, for example, the zeolites will crystallize out ofsolution. In addition, organic polymers can be prepared by delivering amonomer (or monomers) of interest to predefined regions on the substrateusually in the form of a solution. Once the monomer of interest has beendelivered, an initiator is added to each region on the substrate. Thepolymerization reaction is allowed to proceed until the initiator isused up, or until the reaction is terminated in some other manner. Uponcompletion of the polymerization reaction, the solvent can be removedby, for example, evaporation in vacuo.

It will be readily apparent to those of skill in the art that theforegoing synthetic routes are intended to illustrate, and not restrict,the ways in which the reactants can be simultaneously reacted to form atleast two materials on a single substrate. Other synthetic routes andother modifications known to and used by those of skill in the art canalso be used.

VII. Methods for Screening the Array of Materials

Once prepared, the array of materials can be screened in parallel formaterials having useful properties. Either the entire array or,alternatively, a section thereof (e.g., a row of predefined regions) canbe screened in parallel for materials having useful properties. Scanningdetection systems are preferably utilized to screen an array ofmaterials wherein the density of regions per unit area will be greaterthan 0.04 regions/cm², more preferably greater than 0.1 regions/cm²,even more preferably greater than 1 region/cm², even more preferablygreater than 10 regions/cm², and still more preferably greater than 100regions/cm². In most preferred embodiments, scanning detection systemsare preferably utilized to screen an array of materials wherein thedensity of regions per unit area will be greater than 1,000 regions/cm²,more preferably 10,000 regions/cm², even more preferably greater than100,000 regions/cm², and still more preferably 10,000,000 regions/cm².

Accordingly, in a preferred embodiment, the array of materials issynthesized on a single substrate. By synthesizing the array ofmaterials on a single substrate, screening the array for materialshaving useful properties is more easily carried out. Properties whichcan be screened for include, for example, electrical, thermalmechanical, morphological, optical, magnetic, chemical, etc. Moreparticularly, useful properties which can be screened for are set forthin Table I, infra. Any material found to possess a useful property cansubsequently be prepared on a large-scale.

The properties listed in Table I can be screened for using conventionalmethods and devices known to and used by those of skill in the art.Scanning systems which can be used to screen for the properties setforth in Table I include, but are not limited to, the following:scanning Raman spectroscopy; scanning NMR spectroscopy; scanning probespectroscopy including, for example, surface potentialometry, tunnellingcurrent, atomic force, acoustic microscopy, shearing-stress microscopy,ultra fast photo excitation, electrostatic force microscope, tunnelinginduced photo emission microscope, magnetic force microscope, microwavefield-induced surface harmonic generation microscope, nonlinearalternating-current tunnelling microscopy, near-field scanning opticalmicroscopy, inelastic electron tunneling spectrometer, etc.; opticalmicroscopy at different wavelengths; scanning optical ellipsometry (formeasuring dielectric constant and multilayer film thickness); scanningEddy-current microscope; electron (diffraction) microscope, etc.

More particularly, to screen for conductivity and/or superconductivity,one of the following devices can be used: a Scanning RF SusceptibilityProbe, a Scanning RF/Microwave Split-Ring Resonator Detector, or aScanning Superconductors Quantum Interference Device (SQUID) DetectionSystem. To screen for hardness, a nanoindentor (diamond tip) can, forexample, be used. To screen for magnetoresistance, a ScaningRF/Microwave Split-Ring Resonator Detector or a SQUID Detection Systemcan be used. To screen for crystallinity, infrared or Raman spectroscopycan be used. To screen for magnetic strength and coercivity, a ScanningRF Susceptibility Probe, a Scanning RF/Microwave Split-Ring ResonatorDetector, a SQUID Detection System or a Hall probe can be used. Toscreen for fluorescence, a photodetector can be used. Other scanningsystems known to those of skill in the art can also be used.

TABLE I EXAMPLES OF PROPERTIES WHICH CAN BE SCREENED FOR ELECTRICAL:SUPERCONDUCTIVITY CRITICAL CURRENT CRITICAL MAGNETIC FIELD CONDUCTIVITYRESISTIVITY FOR RESISTIVE FILMS DIELECTRIC CONSTANT DIELECTRIC STRENGTHDIELECTRIC LOSS STABILITY UNDER BIAS POLARIZATION PERMITTIVITYPIEZOELECTRICITY ELECTROMIGRATION THERMAL: COEFFICIENT OF EXPANSIONTHERMAL CONDUCTIVITY TEMPERATURE VARIATION VOLATILITY & VAPOR PRESSUREMECHANICAL: STRESS ANISOTROPY ADHESION HARDNESS DENSITY DUCTILITYELASTICITY POROSITY MORPHOLOGY: CRYSTALLINE OR AMORPHOUS MICROSTRUCTURESURFACE TOPOGRAPHY CRYSTALLITE ORIENTATION OPTICAL: REFRACTIVE INDEXABSORPTION BIREFRINGENCE SPECTRAL CHARACTERISTICS DISPERSION FREQUENCYMODULATION EMISSION MAGNETIC: SATURATION FLUX DENSITY MAGNETORESISTANCEMAGNETORESTRICTION COERCIVE FORCE MAGNETIC: PERMEABILITY CHEMICAL:COMPOSITION COMPLEXATION ACIDITY-BASICITY CATALYSIS IMPURITIESREACTIVITY WITH SUBSTRATE CORROSION & EROSION RESISTANCE

The arrays of the present invention can be screened sequentially or,alternatively, they can be screened in parallel using a scanning system.For instance, the array of materials can be sequentially screened forsuperconductivity using, for example, magnetic decoration (Bitterpattern) and electron holography. Alternatively, the array of materialscan be scanned for superconductivity using, for example, a Hall-probe,magnetic force microscopy, SQUID microscopy, a AC susceptibilitymicroscope, a microwave absorption microscope, an Eddy currentmicroscope, etc.

In a presently preferred embodiment, a scanning detection system isemployed. In one embodiment, the substrate having an array of materialsthereon is fixed and the detector has X-Y motion. In this embodiment,the substrate is placed inside a sealed chamber, close to the detector.The detector (e.g., an RF Resonator, a SQUID detector, etc.) is attachedto a rigid rod with low thermal conductivity coupled to an X-Ypositioning table at room temperature with a scanning range of up to 1inch and a 2 μm spatial resolution. The position of the detector iscontrolled using stepping motors (or servomotors) connected to acomputer-controlled positioner. The temperature of the detector and thesubstrate can be lowered via helium exchange gas by liquid heliumreservoir located around the chamber. This scanning system can beoperated at temperatures ranging from 600° K down to 4.2° K (whenimmersed in liquid helium).

In another embodiment, the detector is fixed and the substrate having anarray of materials thereon has R-θ motion. In this embodiment, thesubstrate is placed on a rotating stage (e.g., a spur gear) driven by agear rack which is coupled to a micrometer and a stepping motor. Thisrotating stage is located on a cryogenic sliding table which is drivenby a separate micrometer and stepping motor system. This system iscapable of scanning an area having a 1 inch radius with a 1 μm spatialresolution. The scanning and probing are controlled through the use of acomputer. As with the other embodiment, the temperature of the detectorand the substrate can be lowered via helium exchange gas using a liquidhelium reservoir located around the chamber. This scanning system can beoperated at temperatures ranging from 600° K down to 4.2° K (whenimmersed in liquid helium).

Using either of the foregoing embodiments, a Scanning RF SusceptibilityDetection System can, for example, be used to detect thesuperconductivity of a large array of materials (see, e.g., FIG. 7).Using photolithographic techniques, a micro (about 1×1 mm²) spiral coilcan be fabricated to probe the conductivity of a sample adjacent to thecoil. The signals are picked up by a phase-sensitive detectionelectronic circuit. Thereafter, the data is analyzed by a computer toobtain a correlation between the properties and stoichiometry of a givensample. If desired, analytical results can be fed back to the deliverysystem so that the system can “zoom in” on the most promisingstoichiometry in the next synthesis cycle.

Moreover, a superconducting microcircuit implementation of a parallel LCresonance circuit can be used to scan the array of materials for thosethat are superconducting. A parallel LC circuit is simply an inductor inparallel with a capacitor. The electrical properties of both circuitelements give the circuit a resonance frequency where a maximum amountof input voltage is transmitted through to the output. The sharpness ofthe peak, conventionally measured by its Q value, is determined by thematerials used in the circuit, whereas the frequency of the resonance isset by the capacitance and the inductance. It has been determined thatmanufacturing the circuit out of a superconducting material, such asniobium, gives a very high Q value, i.e., a Q value on the order of10,000 or more. This is in contrast to commercially available,non-superconducting capacitors and inductors which generally give Qvalues on the order of hundreds. The steep peak of the niobium circuitgives rise to high sensitive detection.

In this system, actual detection is done by the induction coil. Theinductance of an inductor is a function of the magnetic field geometrythrough its coils. In the presence of a nearby superconducting sample,the magnetic field through the inductor is distorted by the expulsion offield by the material (i.e., the Meissner effect). This, in turn,changes the inductance and shifts the resonance. By following theresonance, one can readily determine when a material is superconducting.

In this scanning device, the total circuit is approximately 5 mm×2.5 mm,with an active area equal to approximately one-fourth of that. The coilis a spiral coil having dimensions of about 1.5 mm per side, and thecapacitor is a two-plate niobium capacitor with a SiO₂ dielectric (i.e.,insulating) layer. SQUID magnetometers have achieved spatial resolutionsof 10 μm, but their sensitivities have been limited by noise present inthe Josephson junction. In the scanning device of the present invention,however, the device is unencumbered by noise from the Josephson junctionand, thus, a sensitivity for samples of 1 μm or less can be achieved. Inthis embodiment, sensitivity, rather than spatial resolution, is a morecritical criterion.

It will be readily apparent to those of skill in the art that theforegoing detection systems are intended to illustrate, and notrestrict, the ways in which the array of material can be screened forthose materials having useful properties. Other detection systems knownto and used by those of skill in the art can similarly be used.

VIII. Alternative Embodiments

In another embodiment of the present invention, at least two differentarrays of materials are prepared by delivering substantially the samereaction components at substantially identical concentrations topredefined regions on both first and second substrates and, thereafter,subjecting the components on the first substrate to a first set ofreaction conditions and the components on the second substrate to asecond set of reaction conditions in a wide array of compositions. If afirst substrate has, for example, components A and B on a first regionon the substrate and, in addition, components X and Y on a second regionon the substrate, the second substrate is prepared in a manner such thatit has substantially the same components in predefined regions. That isto say, the second substrate is substantially identical to the firstsubstrate in terms of the components contained thereon. As such, in thisexample, the second substrate would also have components A and B on thefirst region of the substrate and, in addition, components X and Y onthe second region on the substrate.

Once the components have been delivered to their appropriate predefinedregions on the substrate, the components on the first substrate arereacted using a first set of reaction conditions, whereas the componentson the second substrate are reacted using a second set of reactionconditions. It will be understood by those of skill in the art that thecomponents on the first substrate can be reacted under a first set ofreaction conditions at the same time as the components on the secondsubstrate are reacted under a second set of reaction conditions or,alternatively, the components on the first substrate can be reactedunder a first set of reaction conditions either before or after thecomponents on the second substrate are reacted under a second set ofreaction conditions.

In this embodiment, the effects of various reaction parameters can bestudied and, in turn, optimized. Reaction parameters which can be variedinclude, for example, reactant amounts, reactant solvents, reactiontemperatures, reaction times, the pressures at which the reactions arecarried out, the atmospheres in which the reactions are conducted, therates at which the reactions are quenched, etc. Other reactionparameters which can be varied will be apparent to those of skill in theart. Alternatively, the first set of reaction conditions can be the sameas the second set of reaction conditions, but, in this embodiment, theprocessing steps after the components on the first and second substrateshave been reacted would differ from the first substrate to the secondsubstrate. For example, the first substrate can be exposed to oxygen atelevated temperatures, while the second substrate is not processed atall.

Alternatively, in another aspect of this embodiment, the first substratehaving component A on the first region of the substrate and component Xon the second region of the substrate is exposed to a particular set ofreaction conditions (e.g., exposed to oxygen at elevated temperatures),while the second substrate also having component A on the first regionof the substrate and component X on the second region of the substrateis not exposed to such reaction conditions. Thereafter, component B isdelivered to the first region of both the first and second substrates,and component Y is delivered to the second region of both the first andsecond substrates. Once the desired components have been delivered tothe first and second regions on the first and second substrates, thecomponents are simultaneously reacted under substantially identicalreaction conditions. This particular embodiment allows one to determinethe effects intermediate processing steps have on a particular array ofmaterials. As set forth above, any of a number of different reactionparameters can be varied.

In still another embodiment of the present invention, a method isprovided for producing an array of materials varying from one another interms of chemical composition and component stoichiometries. In thismethod, a reactant component can be delivered to a particular predefinedregion(s) in a gradient of stoichiometries. Moreover, multiple reactantcomponents can be delivered to a particular predefined region(s) in agradient of stoichiometries. For example, a first component of a firstmaterial is deposited in a gradient of stoichiometries from left toright on the first reaction region. Thereafter, a first reactioncomponent of a second material is deposited in a gradient ofstoichiometries from left to right on the second reaction region.Thereafter, a second component of the first material is deposited in agradient of stoichiometries from top to bottom on the first reactionregion. Thereafter, a second component of the second material isdeposited in a gradient of stoichiometries from top to bottom on thesecond reaction region. Once the components have been delivered to thesubstrate, the components are simultaneously reacted to form materialsvarying from one another in terms of chemical composition and chemicalstoichiometries.

In yet another embodiment of the present invention, a material having auseful property is provided. The material is prepared by a processcomprising the steps of: (a) forming an array of different materials ona single substrate; (b) screening the array for a material having auseful property; and (c) making additional amounts of the materialhaving the useful property. Such materials include, for example,intermetallic materials, metal alloys, ceramic materials, organometallicmaterials, organic polymers, composite materials (e.g., inorganiccomposites, organic composites, or combinations thereof), etc. Inaddition, useful properties include, for example, electrical, thermal,mechanical, morphological, optical, magnetic, chemical, etc.

It will be understood by those of skill in the art that the foregoingdiscussions directed to the various delivery techniques, syntheticroutes, screening methods, etc. are fully applicable to the aboveembodiments of the present invention.

IX. EXAMPLES

The following examples are provided to illustrate the efficacy of theinventions herein.

A. Synthesis of An Array of Copper Oxide Thin-Film Materials

This example illustrates the synthesis and screening of an array ofcopper oxide thin-film materials. The reactants were delivered to a 1.25cm×1.25 cm MgO substrate with a (100) polished surface. The substratehaving 16 predefined regions thereon was contained in a reaction chamberin vacuo. The reactants were delivered to the substrate in the form ofthin-films using a sputtering system in combination with binary maskingtechniques. The binary mask was made of stainless steel. A RF magnetrongun sputtering system was used to deliver the reactant components to thepredefined regions on the substrate. The RF magnetron sputtering gun(Mini-mak manufactured by US, Inc., Campbell, Calif.) used was about 1.3inches in diameter. With RF input power (supplied by a Plasmtherm-2000with a matching network) of 50 to about 200 W, deposition rates rangedfrom about 0.3 Å/s to about 2 A/s for the five different reactantcomponents. The RF magnetron sprayer was positioned about 3 to 4 inchesabove the substrate and the uniformity of deposited film was about 5%over a 1 to 2 inch diameter area. The sputtering gas flow (Ar or Ar andO₂) was controlled by metering valves and differential pumping through amanual gate valve. To achieve a high deposition rate, it was determinedthat the best gas pressure range was about 5 to 15 mTorr. The partialpressure of each gas component in the chamber was monitored using aresidual gas analyzer (Micropole Sensor by Ferran Scientific, San Diego,Calif.) directly up to 15 mTorr without differential pumping.

The reactant components used to generate the array of copper oxidematerials were as follows: CuO, Bi₂O₃, CaO, PbO and SrCo₃. CuO was usedas the base element in an effort to discover new copper oxide materialsand, thus, this component was delivered to each of the 16 predefinedregions on the substrate. Prior to delivering the component of interestto the predefined regions on the substrate, the base air pressure of thereaction chamber was lowered, within 10 to 15 minutes, to about 10⁻⁵ to10⁻⁶ Torr by a 250 1/s turbo pump and, if necessary, it was furtheredlowered to 10⁻⁸ Torr using extended pumping time in combination withheating the reaction chamber to about 100° C. to about 150° C. Sinceonly a single RF magnetron gun sputtering system was employed, thevacuum was broken and reestablished each time the component was changed.The film deposition thickness was monitored using a crystalmicro-balance (STM-100 by Sycon Instruments, Syracuse, N.Y.). Since theposition of crystal micro-balance was not located at exactly the sameposition as the substrate, it was necessary to calibrate the thicknessmonitor reading for each component with a profilometer.

The reactant components were delivered to the MgO substrate in thefollowing order: Bi₂O₃, PbO, CuO, CaO and SrCO₃. The stoichiometry wasdesigned so that each of the five components was present in equal molaramounts, i.e., 1Bi:1Pb:1Cu:1Sr:1Ca as deposited film. The totalthickness of the film was about 0.5 μm for a five layered site. Thethickness of each of the individual films as well as the sputteringrates at which each of the components were deposited are set forth inTable II, supra.

TABLE II DEPOSITION THICKNESS AND SPUTTERING RATE FOR THE COMPONENTSUSED TO GENERATE AN ARRAY OF COPPER OXIDES Component DepositionThickness Sputtering Rate Bi₂O₃ 1200 Å  2 Å/Sec PbO 970 Å 1.6 Å/Sec  CuO 540 Å 1 Å/Sec SrCO₃ 1650 Å  3 Å/Sec CaO 720 Å 3 Å/Sec

Once the components of interest were delivered to the 16 predefinedregions on the substrate as illustrated in FIG. 8, the substrate wasplaced in a furnace, and the components were subsequently reacted. FIG.9 is a photograph of the array of 16 different compounds on the 1.25cm×1.25 cm MgO substrate. The color of each site is the natural color ofreflected light from a white light source at an angle. The componentswere simultaneously reacted using the following heating and coolingprocedure: 50° C. to 725° C. in 2 hr., 725° C. to 820° C. in 1 hr., 820°C. to 840° C. in 0.5 hr. and 840° C. to 750° C. in 0.5 hr. Once thesubstrate cooled to a temperature of about 750° C., the power was turnedoff. The heating and cooling procedure was performed in ambientatmosphere. No apparent evaporation or melting was observed.

Once reacted, each of the 16 predefined reaction regions were screenedfor resistance. In doing so, it was found that two of the predefinedregions contained materials which are conducting. Contacts were put onthese two sites in in-line 4-probe configuration, and it was determinedthat the contact resistances are less than hundred ohms (Ω). Thereafter,the samples were cooled down to 4.2° K in a liquid helium cryostat tomeasure resistivity as a function of temperature. Factory calibratedCemox™ resistance temperature sensor (LakeShore) was used to measuretemperature. FIGS. 10A and 10B shows the resistance of the twoconducting materials as a function of temperature. The BiPbCuSrCamaterial has a metallic conductivity (resistance decrease withtemperature) from room temperature down to about 100° K, whereas theBiCuSrCa material has a rather flat and slightly upward temperaturedependence resistance. Superconducting critical temperatures (T_(c)) forboth samples are about 100° K. Evidence of two superconducting phases inthe resistivity measurement was not observed.

B. Synthesis of An Array of 16 Different Organic Polymers

This example illustrates the possible synthesis of an array of 16different organic polymers formed by the polymerization of styrene withacrylonitrile. A 3 cm×3 cm pyrex substrate having 16 predefined regionsthereon is used in this example. Each of the predefined regions is 3mm×3 mm×5 mm and, thus, the volume of each predefined region is about 45μL. To ensure that the reactants in a given region do not move toadjacent regions, 35 μL reaction volumes will be used.

A 2 M solution of the styrene monomer in toluene and a 2 M solution ofacrylonitrile in toluene are used. The initiator used to initiate thepolymerization reaction is benzoyl peroxide. A 70 mM solution of benzoylperoxide in toluene is used. The initiator is present in each of thereactions at a 10 mM concentration. The styrene, acrylonitrile andbenzoyl peroxide solutions are delivered to each of the 16 predefinedregions on the substrate using an ink-jet dispenser having threenozzles. The first nozzles is connected to a reservoir containing the 2M solution of styrene in toluene, the second nozzle is connected to areservoir containing the 2 M solution of acrylonitrile in toluene, andthe third nozzle is connected to a reservoir containing the 70 mMsolution of benzoyl peroxide in toluene. The initiator is delivered toeach of the 16 predefined regions only after the monomers have beendelivered.

To generate an array of 16 different polymers of styrene andacrylonitrile, the reactant amounts set forth in Table II, infra, aredelivered to the 16 predefined regions on the substrate. Once themonomers have been delivered to the 16 predefined regions on thesubstrate, 5 μL of the 70 mM initiator solution is added. Thepolymerization reaction is carried out at a temperature of about 60° C.and at ambient pressure. The reactions are allowed to proceed until theterminator is used up. Upon completion of the polymerization reaction,the organic solvent is removed by evaporation in vacuo (100 Torr). Theresulting polymers can be screened for hardness using, for example, ananoindentor (sharp tip).

TABLE III VARIOUS REACTANT COMPONENTS USED TO GENERATE AN ARRAY OF 16DIFFERENT POLYMERS Amount of 2 M Solution Amount of 2 M SolutionReaction Region of Styrene (μL) of Acrylonitrile (μL) 1 30 0 2 28.5 1.53 27 3 4 25.5 4.5 5 24 6 6 22.5 7.5 7 21 9 8 19.5 10.5 9 18 12 10 16.513.5 11 15 15 12 13.5 16.5 13 12 18 14 10.5 19.5 15 9 21 16 7.5 22.5

C. Synthesis of An Array of Zeolites

This example illustrates a possible method for the synthesis of an arrayof different zeolites. The reactants are delivered to a 9 cm×9 cm Teflonsubstrate having 16 predefined regions thereon. The substrate is placedin a sealed container having a temperature of about 100° C. Each of the16 predefined regions on the substrate is a 1 cm×1 cm×2 cm well. Thereactants are delivered to the substrate using a automated pipette.

The five components used to generate the array of zeolites are asfollows: Na₂O.Al₂O₃.5H₂O, KOH, Na₂O.2SiO₂.5H₂O, NaOH and H₂O. The fircomponents are dissolved in water to concentrations of 2.22 M, 2.22 M,8.88 M and 11.1 M, respectively. In delivering the components to thepredefined regions on the substrate, it is important that theNa₂O.2SiO₂.5H₂O solution is added last. The five reactant components aredelivered to the predefined regions on the substrate in the amounts setforth in Table III, supra.

Once the foregoing components have been delivered to the appropriatepredefined regions on the substrate and allowed to react, the array canbe scanned for microstructure using a Raman Light Scattering System.Scanning of the array can begin 2 to 3 hours after the components havebeen delivered to the substrate and can continue for anywhere from 5 to10 days. In this example, Zeolite A will initially be formed at reactionregion 1. With time, however, Zeolite A will be converted to Zeolite P.Zeolite X will be formed at reaction region 3. Sodalite will be formedat reaction region 6. Zeolite L will be formed at reaction region 12. Inaddition, other zeolites may be formed at other reaction regions on thesubstrate.

TABLE IV VARIOUS REACTANT COMPONENTS USED TO GENERATE AN ARRAY OFZEOLITES Amount Amount of 2.2 M of 2.2 M Solution Amount Solution Amountof Na₂O of 8.88 M of Na₂O of 11.1 M .Al₂O₃ Solution .2SiO₂ SolutionAmount Reaction .5H₂O of KOH .5H₂O of NaOH of H₂O Region (μL) (μL) (μL)(μL) (μL) 1 100 0 100 80 480 2 100 0 100 80 1280 3 100 0 200 40 420 4100 0 200 40 1220 5 100 0 100 320 240 6 100 0 100 320 1040 7 100 0 200280 180 8 100 0 200 280 980 9 100 200 100 80 280 10 100 200 100 80 108011 100 200 200 40 220 12 I00 200 200 40 1020 13 100 200 100 320 40 14100 200 100 320 840 15 100 200 200 280 0 16 100 200 200 280 800

D. Synthesis of An Array of Copper Oxide Compounds Using SprayingDeposition Techniques

This example illustrates the synthesis of an array of different copperoxide compounds using spraying deposition techniques. The reactants aredelivered to a 1.25 cm×1.25 cm MgO substrate having 16 predefinedregions thereon. The reactants are delivered in the form of thin-filmsusing a sprayer in combination with physical masking techniques. Thesprayer used in this example is a Sinitek 8700-120MS ultrasonic sprayer.At a water flow rate of 0.26 GPM and a frequency of 120 KHz, thissprayer can generate a cone-line spraying pattern of 2 inches and adroplet diameter of 18 microns.

The four components used in this example to generate the array ofinorganic materials are Bi(NO₃)₃, Cu(NO₃)₃, Ca(NO₃)₃ and Si(NO₃)₃. Thesecomponents were dissolved in water to concentrations of 0.8 M, 2 M, 2 Mand 2 M, respectively. The pH of the Bi(NO₃)₃ solution was about 0.9. Indelivering the reactants to the predefined regions on the substrate, itis important to control the flow rate of the sprayer as well as thetemperature of the substrate so that the reactant droplets dryimmediately upon contact with the substrate surface. The flow rate usedwas kept at about 0.26 GPM, and the temperature of the substrate wasmaintained at about 210° C. In addition, it is important to control thespraying time so that the amount, i.e., moles, of each reactant isapproximately the same. The spraying time was such that each of thethin-layer films deposited on the surface of the substrate had athickness of about 1 to 4 microns.

Using a binary masking strategy, the aqueous solutions of Ca(NO₃)₃,Bi(NO₃)₃, Cu(NO₃)₃ and Si(NO₃)₃ were delivered, in this order, to thesubstrate using the following steps. As mentioned, the MgO substrate had16 predefined regions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15and 16. In a first masking step, regions 9, 10, 11, 12, 13, 14, 15, and16 were masked and an aqueous solution of Ca(NO₃)₃ was delivered to theexposed regions in the form of a thin-film. Thereafter, in a secondmasking step, the mask was repositioned so that regions 3, 4, 7, 8, 11,12, 15 and 16 were masked, and an aqueous solution of Bi(NO₃)₃ wasdelivered to the exposed regions in the form of a thin-film. In a thirdmasking step, regions 5, 6, 7, 8, 13, 14, 15 and 16 were masked, and anaqueous solution of Cu(NO₃)₃ was delivered to the exposed regions in theform of a thin-film. Finally, in a fourth masking step, regions 2, 4, 6,8, 10, 12, 14 and 16 were masked, and an aqueous solution of Si(NO₃)₃was delivered to the exposed regions in the form of a thin-film.

Once the components of interest were delivered to the appropriatepredefined regions on the substrate, the substrate having the array ofreactants thereon was oxidized at 300° C. to remove any nitrogen fromthe array. Thereafter, the substrate was flash heated at 880° C. forabout 2 minutes and rapidly quenched on a copper block. Thereafter, thearray of materials was screened for superconducting material.

E. Synthesis of An Array of Manganese Oxide Thin-film Materials

This example illustrates the possible synthesis and screening of anarray of manganese oxide thin-film materials. The reactants aredelivered to a 1.25 cm×1.25 cm LaAlO₃ substrate with a (100) polishedsurface. The substrate having 16 predefined regions thereon is containedin a reaction chamber in vacuo. The reactants are delivered to thesubstrate in the form of thin-films using a sputtering system incombination with binary masking techniques. The binary mask is made ofstainless steel. A RF magnetron gun sputtering system is used to deliverthe reactant components to the predefined regions on the substrate. TheRF magnetron sputtering gun (Mini-mak manufactured by US, Inc.,Campbell, Calif.) used is about 1.3 inches in diameter. With RF inputpower (supplied by a Plasmtherm-2000 with a matching network) of 50 toabout 200 W, deposition rates ranged from about 0.3 Å/s to about 2 Å/sfor the five different reactant components. The RF magnetron sprayer ispositioned about 3 to 4 inches above the substrate and the uniformity ofdeposited film is about 5% over a 1 to 2 inch diameter area. Thesputtering gas flow (Ar or Ar and O₂) is controlled by metering valvesand differential pumping through a manual gate valve. To achieve a highdeposition rate, it is determined that the best pressure range is about5 to 15 mTorr. The partial pressure of each gas component in the chamberis monitored using a residual gas analyzer (Micropole Sensor by FerranScientific, San Diego, Calif.) directly up to 15 mTorr withoutdifferential pumping.

The reactant components used to generate the array of copper oxidematerials are as follows: MnO₂, La₂O₃, CaO, SrF₂, and BaF₂. MnO₂ is usedas the base element in an effort to discover new manganese oxidematerials and, thus, this component is delivered to each of the 16predefined regions on the substrate. Prior to delivering the componentof interest to the predefined regions on the substrate, the base airpressure of the reaction chamber is lowered, within 10 to 15 minutes, toabout 10⁻⁵ to 10⁻⁶ Torr by a 250 1/s turbo pump and, thereafter, it isfurthered lowered to 10⁻⁸ Torr using extended pumping time incombination with heating the reaction chamber to about 100° C. to about150° C. Since only a single RF magnetron gun sputtering system isemployed, the vacuum is broken and re-established each time thecomponent is changed. The film deposition thickness is monitored using acrystal micro-balance (STM-100 by Sycon Instruments, Syracuse, N.Y.).

The reactant components are delivered to the LaAlO₃ substrate in thefollowing order: MnO₂, La₂O₃, CaO, SrF₂, and BaF₂. The stoichiometry isdesigned so that each of the five components is present in equal molaramounts, i.e., 2Mn: 1La: 1Ca: 1Sr: 1Ba as deposited film. The totalthickness of the film is about 0.4 μm for a five layered site. Thethickness of each of the individual films as well as the sputteringrates at which each of the components are deposited are set forth inTable V, supra.

TABLE V DEPOSITION THICKNESS AND SPUTTERING RATE FOR THE COMPONENTS USEDTO GENERATE AN ARRAY OF MANGANESE OXIDES Component Deposition ThicknessSputtering Rate La₂O₃ 480 Å 0.3 Å/SEC MnO₂ 1000 Å    1 Å/SEC BaF₂ 1040Å  0.3 Å/SEC SrF₂ 860 Å 0.3 Å/SEC CaO 480 Å 0.3 Å/SEC

Once the components of interest are delivered to the 16 predefinedregions on the substrate, the substrate is placed in a furnace, and thecomponents are subsequently reacted. The components are simultaneouslyreacted using the following heating and cooling procedure: 50° C. to840° C. in 2 hr., 840° C. to 900° C. in 0.5 hr. and 900° C. to 840° C.in 0.5 hr. Once the substrate cools to a temperature of about 840° C.,the power is turned off. The heating and cooling procedure is performedin ambient atmosphere. No apparent evaporation or melting is observed.

Once reacted, each of the 16 predefined reaction regions are screenedfor giant magnetoresistant (GMR) materials using a 12 Telsasuperconducting magnet cryostat (manufactured by Janis Research Co.,Inc., Wilmington, Mass.) using contact measurement techniques.Noncontact measurement techniques using similar scanning detectionsystems for high T_(c) materials can also be applied to increase theefficiency and resolution.

F. Synthesis of An Array of 16 Different Zinc Silicate Phosphors

This example illustrates the possible synthesis of an array of 16different zinc silicate phosphors. A 1 mm×1 mm pyrex substrate having 16predefined regions thereon is used in this example. Each of thepredefined regions is 100 μm×100 μm×500 μm and, thus, the volume of eachpredefined region is about 5,000 picoliters. To ensure the reactants ina given region do not move to adjacent regions, 3,000 picoliter reactionvolumes will be used.

The reactants will be delivered simultaneously to each region on thesubstrate using an ink-jet dispenser having three nozzles. The firstnozzle is connected to a reservoir containing a 1M solution of ZnO inwater. To generate an array of 16 different phosphors, the reactantamounts set forth in Table VI, infra, are delivered to the 16 predefinedregions on the substrate. The synthesis reaction is carried out under anitrogen atmosphere for a period of 2 hrs. at 1400° C. Once formed, eachof the 16 predefined reaction regions is screened for electroluminescentmaterials or phosphors by radiating the sample with a specificexcitation wavelength and recording the emission spectra with aPerkin-Elmer LS50 spectrofluorimeter.

TABLE VI VARIOUS REACTANT COMPONENTS USED TO GENERATE AN ARRAY OF ZINCSILICATE PHOSPHORS MnCO₃ Reaction Region SiO₂ (picoliters) ZnO 1 15001425 75 2 1500 1350 150 3 1500 1275 225 4 1500 1200 300 5 1500 1125 3756 1500 1050 450 7 1500 975 525 8 1500 900 600 9 2000 950 50 10 2000 900100 11 2000 850 150 12 2000 800 200 13 2000 750 250 14 2000 700 300 152000 650 350 16 2000 600 400

X. Conclusion

The present invention provides greatly improved methods and apparatusfor the parallel deposition, synthesis and screening of an array ofmaterials on a single substrate. It is to be understood that the abovedescription is intended to be illustrative and not restrictive. Manyembodiments and variations of the invention will become apparent tothose of skill in the art upon review of this disclosure. Merely by wayof example a wide variety of process times, reaction temperatures andother reaction conditions may be utilized, as well as a differentordering of certain processing steps. The scope of the invention should,therefore, be determined not with reference to the above description,but instead should be determined with reference to the appended claimsalong with the full scope of equivalents to which such claims areentitled.

What is claimed is:
 1. A method of evaluating an array of polymericmaterials, the method comprising preparing an array comprising first andsecond non-biological organic polymers on a substrate, the firstnon-biological organic polymer being different from the secondnon-biological organic polymer, the array being prepared by a methodthat includes delivering a first component and a second component of thefirst non-biological organic polymer to a first region of a substrate,delivering a first component and a second component of the secondnon-biological organic polymer to a second region on the substrate,delivering an initiator to the first and second regions of thesubstrate, and polymerizing the delivered first and second components ofthe first non-biological organic polymer to form the firstnon-biological organic polymer at the first region of the substrate, andsimultaneously polymerizing the delivered first and second components ofthe second non-biological organic polymer to form the secondnon-biological organic polymer at the second region of the substrate,and screening the first and second non-biological organic polymers for aproperty of interest selected from the group consisting of a thermalproperty, a mechanical property, a morphological property, a chemicalproperty, an optical property, a magnetic property and an electricalproperty.
 2. The method as recited in claim 1 wherein saidnon-biological organic polymers are selected from the group consistingof homopolymers, copolymers and higher-ordered polymers.
 3. The methodas recited in claim 1 wherein said non-biological organic polymers areselected from the group consisting of natural polymers, syntheticpolymers, cross-linked polymers and non-cross-linked polymers.
 4. Themethod of claim 1 wherein said non-biological organic polymers areselected from the group consisting of polyurethanes, polyesters,polycarbonates, polyethyleneimines, polyacetates, polystyrenes,polyamides, polyanilines, polyacetylenes and polypyrroles.
 5. The methodas recited in claim 1 wherein said first component of said firstmaterial and said second component of said first material aresimultaneously delivered to said first region on said single substrate.6. The method as recited in claim 1 wherein said first component of saidfirst material and said first component of said second material aresimultaneously delivered to said first region and said second region onsaid single substrate, respectively.
 7. The method as recited in claim 1wherein said first component of said first material and said firstcomponent of said second material are the same, but are offered indifferent concentrations.
 8. The method as recited in claim 1 whereinsaid second component of said first material and said second componentof said second material are the same, but are offered in differentconcentrations.
 9. The method as recited in claim 1 wherein thecomponents of said materials are delivered to said first and secondregions on said substrate from a dispenser.
 10. The method as recited inclaim 9 wherein said dispenser is a pipette.
 11. The method as recitedin claim 9 wherein said dispenser is selected from the group consistingof a pulse pressure ink-jet dispenser, a bubble jet ink-jet dispenserand a slit jet ink-jet dispenser.
 12. The method as recited in claim 1wherein said steps of delivering said components each comprises thefollowing steps: (i) identifying a reference point on said substrate;(ii) moving a dispenser of said component a fixed distance and directionfrom said reference point such that said dispenser is positionedapproximately above said first region of said substrate; (iii)delivering said component to said first region; and (iv) repeating steps(ii) and (iii) for each remaining component for each remaining region.13. The method as recited in claim 1 wherein there is a sufficientamount of space between each of said regions on said single substratesuch that said components cannot interdiffuse between said regions. 14.A method for evaluating polymeric materials, the method comprisingdelivering one or more monomers of non-biological organic polymers toten or more regions of a substrate, delivering an initiator to the tenor more regions of the substrate, simultaneously polymerizing thedelivered monomers to form ten or more different non-biological organicpolymers on the substrate, and screening the ten or more non-biologicalorganic polymers for a property of interest selected from the groupconsisting of a thermal property, a mechanical property, a morphologicalproperty, a chemical property, an optical property, a magnetic propertyand an electrical property.
 15. The method of claim 14 wherein the tenor more non-biological organic polymers are homopolymers.
 16. The methodof claim 14 wherein the ten or more non-biological organic polymers arecopolymers.
 17. A method for preparing an array of polymeric materials,the method comprising delivering one or more monomers of a firstnon-biological organic polymer to a first region on the substrate,delivering one or more monomers of a second non-biological organicpolymer to a second region on the substrate, delivering an initiator tothe first and second regions of the substrate, polymerizing thedelivered monomers of the first non-biological organic polymer, suchthat the monomers react, without linear, stepwise coupling thereof, toform the first non-biological organic polymer, and simultaneously,polymerizing the delivered monomers of the second non-biological organicpolymer, such that the monomers react, without linear, stepwise couplingthereof, to form the second non-biological organic polymer, the secondnon-biological organic polymer being different from the firstnon-biological organic polymer.
 18. The method of claim 17 wherein thefirst and second non-biological organic polymers are homopolymers. 19.The method of claim 17 wherein the first and second non-biologicalorganic polymers are copolymers.
 20. A method for preparing an array ofpolymeric materials, the method comprising delivering one or moremonomers of a first non-biological organic polymer to a first region onthe substrate, delivering one or more monomers of a secondnon-biological organic polymer to a second region on the substrate,delivering an initiator to the first and second regions of thesubstrate, polymerizing the delivered monomers of the firstnon-biological organic polymer, to form the first non-biological organicpolymer, polymerizing the delivered monomers of the secondnon-biological organic polymer to form the second non-biological organicpolymer, and independently controlling the polymerization reactionconditions at the first region and the second region of the substrate.21. The method of claim 20 wherein the first and second non-biologicalorganic polymers are homopolymers.
 22. The method of claim 20 whereinthe first and second non-biological organic polymers are copolymers. 23.The method of claim 20 wherein the delivered first and second componentsof each of the first and second non-biological organic polymers aresimultaneously polymerized.
 24. The method of claim 20 wherein thetemperatures at the first region and the second region of the substrateare independently controlled.
 25. The method of claim 20 wherein thereaction times at the first region and the second region of thesubstrate are independently controlled.
 26. The method of claim 20wherein the reaction solvents at the first region and the second regionof the substrate are independently controlled.
 27. The method of claim20 wherein the reaction conditions are controllably varied between thefirst region and the second region of the substrate.
 28. A method forpreparing an array of polymeric materials, the method comprising formingten or more different non-biological organic polymers on a substrate,each of the ten or more non-biological organic polymers comprising afirst component and a second component, the first component being thesame between the ten or more non-biological organic polymers, thepolymers being formed by a method that includes delivering the firstcomponent of the ten or more non-biological organic polymers in agradient of stoichiometries to ten or more regions of the substrate,delivering the second component of the ten or more non-biologicalorganic polymers to the ten or more regions of the substrate, deliveringan initiator to the ten or more regions of the substrate, andpolymerizing the delivered first and second components of the ten ormore non-biological organic polymers to form the ten or morenon-biological organic polymers.
 29. The method of claim 28 wherein thesecond component is the same between the ten or more non-biologicalorganic polymers.
 30. The method of claim 28 wherein the secondcomponent is the same between the ten or more non-biological organicpolymers, and the second component is delivered in a gradient ofstoichiometries to the ten or more regions of the substrate.
 31. Amethod for evaluating polymeric materials, the method comprisingdelivering one or more monomers of a first non-biological organicpolymer to a first region on a substrate, delivering one or moremonomers of a second non-biological organic polymer to a second regionon the substrate, delivering an initiator to the first and secondregions of the substrate, polymerizing the delivered monomers of thefirst non-biological organic polymer, such that the monomers react,without linear, stepwise coupling thereof, to form the firstnon-biological organic polymer, and simultaneously, polymerizing thedelivered monomers of the second non-biological organic polymer, suchthat the monomers react, without linear, stepwise coupling thereof, toform the second non-biological organic polymer, the secondnon-biological organic polymer being different from the firstnon-biological organic polymer, and screening the first and secondnon-biological organic polymers for a property of interest selected fromthe group consisting of a thermal property, a mechanical property, amorphological property, a chemical property, an optical property, amagnetic property and an electrical property.
 32. The method of claim 31wherein the first and second regions of the substrate are defined byphysical barriers selected from the group consisting of dimples, wellsand vessels, and the first and second non-biological organic polymersare screened in parallel for a property selected from the groupconsisting of a thermal property, a mechanical property, and a chemicalproperty.
 33. A method for evaluating polymeric materials, the methodcomprising delivering one or more monomers of a first non-biologicalorganic polymer to a first region on the substrate, delivering one ormore monomers of a second non-biological organic polymer to a secondregion on the substrate, delivering an initiator to the first and secondregions of the substrate, polymerizing the delivered monomers of thefirst non-biological organic polymer, to form the first non-biologicalorganic polymer, polymerizing the delivered monomers of the secondnon-biological organic polymer to form the second non-biological organicpolymer, independently controlling the polymerization reactionconditions at the first region and the second region of the substrate,and screening the first and second non-biological organic polymers for aproperty of interest selected from the group consisting of a thermalproperty, a mechanical property, a morphological property, a chemicalproperty, an optical property, a magnetic property and an electricalproperty.
 34. The method of claim 33 wherein the first and secondregions of the substrate are defined by physical barriers selected fromthe group consisting of dimples, wells and vessels, and the first andsecond non-biological organic polymers are screened in parallel for aproperty selected from the group consisting of a thermal property, amechanical property, and a chemical property.
 35. A method forevaluating polymeric materials, the method comprising forming ten ormore different non-biological organic polymers on a substrate, each ofthe ten or more non-biological organic polymers comprising a firstcomponent and a second component, the first component being the samebetween the ten or more non-biological organic polymers, the polymersbeing formed by a method that includes delivering the first component ofthe ten or more non-biological organic polymers in a gradient ofstoichiometries to ten or more regions of the substrate, delivering thesecond component of the ten or more non-biological organic polymers tothe ten or more regions of the substrate, delivering an initiator to theten or more regions of the substrate, and polymerizing the deliveredfirst and second components of the ten or more non-biological organicpolymers to form the ten or more non-biological organic polymers, andscreening the ten or more non-biological organic polymers for a propertyof interest selected from the group consisting of a thermal property, amechanical property, a morphological property, a chemical property, anoptical property, a magnetic property and an electrical property. 36.The method of claim 35 wherein the ten or more regions of the substrateare defined by physical barriers selected from the group consisting ofdimples, wells and vessels, and the ten or more non-biological organicpolymers are screened in parallel for a property selected from the groupconsisting of a thermal property, a mechanical property and a chemicalproperty.
 37. The method as recited in claims 28 or 35 wherein saiddelivered components are simultaneously polymerized.
 38. The method asrecited in claims 1, 17, 20, 31 or 33 wherein at least 10 differentmaterials are synthesized on said substrate.
 39. The method as recitedin claims 1, 14, 17, 20, 28, 31, 33 or 35 wherein at least 100 differentmaterials are synthesized on said substrate.
 40. The method as recitedin claims 1, 14, 17 or 31 wherein at least 1000 different materials aresynthesized on said substrate.
 41. The method as recited in claims 1,14, 17 or 31 wherein at least 10⁶ different materials are synthesized onsaid substrate.
 42. The method as recited in claims 1, 14, 17 or 31wherein at least 100 different materials are synthesized on saidsubstrate, and each different material is contained within an area ofabout 1 mm² or less.
 43. The method as recited in claims 1, 14, 31, 33or 35 wherein said property of interest is an optical property.
 44. Themethod as recited in claim 43 wherein said optical property is measuredusing light scattering techniques.
 45. The method as recited in claims1, 14, 31, 33 or 35 wherein said property of interest is a chemicalproperty.
 46. The method of claims 1, 14, 31, 33 or 35 wherein the arrayof non-biological organic polymers is screened for a thermal property.47. The method of claims 1, 14, 31, 33 or 35 wherein the array ofnon-biological organic polymers is screened for a mechanical property.48. The method of claims 1, 14, 31, 33 or 35 wherein the array ofnon-biological organic polymers is screened for a morphologicalproperty.
 49. The method as recited in claims 1, 14, 31, 33 or 35wherein said array of materials is screened in parallel.
 50. The methodas recited in claims 1, 14, 31, 33 or 35 wherein said array of materialsis screened sequentially.
 51. A method for evaluating styrene copolymermaterials, the method comprising delivering one or more monomers of afirst styrene copolymer to a first region on a substrate, the firstregion of the substrate being defined by physical barriers selected fromthe group consisting of dimples, wells and vessels, delivering one ormore monomers of a second styrene copolymer to a second region on thesubstrate, the second region of the substrate being defined by physicalbarriers selected from the group consisting of dimples, wells andvessels, the delivery of the one or more monomers of the second styrenecopolymer to the second region of the substrate being simultaneous withthe delivery of the one or more monomers of the first styrene copolymerto the first region of the substrate, polymerizing the deliveredmonomers of the first styrene copolymer, such that the monomers react,without linear, stepwise coupling thereof, to form the first styrenecopolymer without covalent bonding to the substrate, and simultaneously,polymerizing the delivered monomers of the second styrene copolymer,such that the monomers react, without linear, stepwise coupling thereof,to form the second styrene copolymer without covalent bonding to thesubstrate, the second styrene copolymer being different from the firststyrene copolymer, and screening the first and second styrene copolymersin parallel for a chemical property.
 52. A method for preparing an arrayof styrene copolymer materials, the method comprising delivering one ormore monomers of a first styrene copolymer to a first region on asubstrate, the first region of the substrate being defined by physicalbarriers selected from the group consisting of dimples, wells andvessels, delivering one or more monomers of a second styrene copolymerto a second region on the substrate, the second region of the substratebeing defined by physical barriers selected from the group consisting ofdimples, wells and vessels, the delivery of the one or more monomers ofthe second styrene copolymer to the second region of the substrate beingsimultaneous with the delivery of the one or more monomers of the firststyrene copolymer to the first region of the substrate, polymerizing thedelivered monomers of the first styrene copolymer, such that themonomers react, without linear, stepwise coupling thereof, to form thefirst styrene copolymer without covalent bonding to the substrate, andsimultaneously, polymerizing the delivered monomers of the secondstyrene copolymer, such that the monomers react, without linear,stepwise coupling thereof, to form the second styrene copolymer withoutcovalent bonding to the substrate, the second styrene copolymer beingdifferent from the first styrene copolymer.